Revert "Performance: Remap multiple items in UI"

This reverts commit 948211679f2a0681421160be0d3b90f507bc0be7.
This commit introduced some regressions in the test suite.
As this change is a core part of blender Bastien and I decided to revert
it as the solution isn't clear and needs more investigation.

The following tests FAILED:
	 62 - blendfile_liblink (SEGFAULT)
	 63 - blendfile_library_overrides (SEGFAULT)

It fails in (id_us_ensure_real)

26 files changed, 304 insertions, 713 deletions

diff --git a/source/blender/blenkernel/BKE_lib_remap.h b/source/blender/blenkernel/BKE_lib_remap.h
index cc970342fbb..d8842dbce7f 100644
--- a/source/blender/blenkernel/BKE_lib_remap.h
+++ b/source/blender/blenkernel/BKE_lib_remap.h
@@ -38,9 +38,6 @@
 extern "C" {
 #endif
 
-struct ID;
-struct IDRemapper;
-
 /* BKE_libblock_free, delete are declared in BKE_lib_id.h for convenience. */
 
 /* Also IDRemap->flag. */
@@ -101,19 +98,6 @@ enum {
 };
 
 /**
- * Replace all references in given Main using the given \a mappings
- *
- * \note Is preferred over BKE_libblock_remap_locked due to performance.
- */
-void BKE_libblock_remap_multiple_locked(struct Main *bmain,
-                                        const struct IDRemapper *mappings,
-                                        const short remap_flags);
-
-void BKE_libblock_remap_multiple(struct Main *bmain,
-                                 const struct IDRemapper *mappings,
-                                 const short remap_flags);
-
-/**
  * Replace all references in given Main to \a old_id by \a new_id
  * (if \a new_id is NULL, it unlinks \a old_id).
  *
@@ -162,61 +146,12 @@ void BKE_libblock_relink_to_newid(struct Main *bmain, struct ID *id, int remap_f
     ATTR_NONNULL();
 
 typedef void (*BKE_library_free_notifier_reference_cb)(const void *);
-typedef void (*BKE_library_remap_editor_id_reference_cb)(const struct IDRemapper *mappings);
+typedef void (*BKE_library_remap_editor_id_reference_cb)(struct ID *, struct ID *);
 
 void BKE_library_callback_free_notifier_reference_set(BKE_library_free_notifier_reference_cb func);
 void BKE_library_callback_remap_editor_id_reference_set(
     BKE_library_remap_editor_id_reference_cb func);
 
-/* IDRemapper */
-struct IDRemapper;
-typedef enum IDRemapperApplyResult {
-  /** No remapping rules available for the source. */
-  ID_REMAP_RESULT_SOURCE_UNAVAILABLE,
-  /** Source isn't mappable (e.g. NULL). */
-  ID_REMAP_RESULT_SOURCE_NOT_MAPPABLE,
-  /** Source has been remapped to a new pointer. */
-  ID_REMAP_RESULT_SOURCE_REMAPPED,
-  /** Source has been set to NULL. */
-  ID_REMAP_RESULT_SOURCE_UNASSIGNED,
-} IDRemapperApplyResult;
-
-typedef enum IDRemapperApplyOptions {
-  ID_REMAP_APPLY_UPDATE_REFCOUNT = (1 << 0),
-  ID_REMAP_APPLY_ENSURE_REAL = (1 << 1),
-
-  ID_REMAP_APPLY_DEFAULT = 0,
-} IDRemapperApplyOptions;
-
-typedef void (*IDRemapperIterFunction)(struct ID *old_id, struct ID *new_id, void *user_data);
-
-/**
- * Create a new ID Remapper.
- *
- * An ID remapper stores multiple remapping rules.
- */
-struct IDRemapper *BKE_id_remapper_create(void);
-
-void BKE_id_remapper_clear(struct IDRemapper *id_remapper);
-bool BKE_id_remapper_is_empty(const struct IDRemapper *id_remapper);
-/** Free the given ID Remapper. */
-void BKE_id_remapper_free(struct IDRemapper *id_remapper);
-/** Add a new remapping. */
-void BKE_id_remapper_add(struct IDRemapper *id_remapper, struct ID *old_id, struct ID *new_id);
-
-/**
- * Apply a remapping.
- *
- * Update the id pointer stored in the given r_id_ptr if a remapping rule exists.
- */
-IDRemapperApplyResult BKE_id_remapper_apply(const struct IDRemapper *id_remapper,
-                                            struct ID **r_id_ptr,
-                                            IDRemapperApplyOptions options);
-bool BKE_id_remapper_has_mapping_for(const struct IDRemapper *id_remapper, uint64_t type_filter);
-void BKE_id_remapper_iter(const struct IDRemapper *id_remapper,
-                          IDRemapperIterFunction func,
-                          void *user_data);
-
 #ifdef __cplusplus
 }
 #endif
diff --git a/source/blender/blenkernel/BKE_screen.h b/source/blender/blenkernel/BKE_screen.h
index c85ae04a492..63f6fca2a9d 100644
--- a/source/blender/blenkernel/BKE_screen.h
+++ b/source/blender/blenkernel/BKE_screen.h
@@ -38,7 +38,6 @@ struct BlendLibReader;
 struct BlendWriter;
 struct Header;
 struct ID;
-struct IDRemapper;
 struct LibraryForeachIDData;
 struct ListBase;
 struct Menu;
@@ -118,7 +117,10 @@ typedef struct SpaceType {
   bContextDataCallback context;
 
   /* Used when we want to replace an ID by another (or NULL). */
-  void (*id_remap)(struct ScrArea *area, struct SpaceLink *sl, const struct IDRemapper *mappings);
+  void (*id_remap)(struct ScrArea *area,
+                   struct SpaceLink *sl,
+                   struct ID *old_id,
+                   struct ID *new_id);
 
   int (*space_subtype_get)(struct ScrArea *area);
   void (*space_subtype_set)(struct ScrArea *area, int value);
diff --git a/source/blender/blenkernel/CMakeLists.txt b/source/blender/blenkernel/CMakeLists.txt
index 6d6579f49f6..41ca8084849 100644
--- a/source/blender/blenkernel/CMakeLists.txt
+++ b/source/blender/blenkernel/CMakeLists.txt
@@ -179,7 +179,6 @@ set(SRC
   intern/lib_id.c
   intern/lib_id_delete.c
   intern/lib_id_eval.c
-  intern/lib_id_remapper.cc
   intern/lib_override.c
   intern/lib_query.c
   intern/lib_remap.c
@@ -824,7 +823,6 @@ if(WITH_GTESTS)
     intern/idprop_serialize_test.cc
     intern/lattice_deform_test.cc
     intern/layer_test.cc
-    intern/lib_id_remapper_test.cc
     intern/lib_id_test.cc
     intern/lib_remap_test.cc
     intern/tracking_test.cc
diff --git a/source/blender/blenkernel/intern/lib_id_delete.c b/source/blender/blenkernel/intern/lib_id_delete.c
index f4dd67cac28..6d2e89187f7 100644
--- a/source/blender/blenkernel/intern/lib_id_delete.c
+++ b/source/blender/blenkernel/intern/lib_id_delete.c
@@ -154,10 +154,7 @@ void BKE_id_free_ex(Main *bmain, void *idv, int flag, const bool use_flag_from_i
     }
 
     if (remap_editor_id_reference_cb) {
-      struct IDRemapper *remapper = BKE_id_remapper_create();
-      BKE_id_remapper_add(remapper, id, NULL);
-      remap_editor_id_reference_cb(remapper);
-      BKE_id_remapper_free(remapper);
+      remap_editor_id_reference_cb(id, NULL);
     }
   }
 
@@ -295,40 +292,32 @@ static size_t id_delete(Main *bmain, const bool do_tagged_deletion)
      * Note that we go forward here, since we want to check dependencies before users
      * (e.g. meshes before objects).
      * Avoids to have to loop twice. */
-    struct IDRemapper *remapper = BKE_id_remapper_create();
     for (i = 0; i < base_count; i++) {
       ListBase *lb = lbarray[i];
       ID *id, *id_next;
-      BKE_id_remapper_clear(remapper);
 
       for (id = lb->first; id; id = id_next) {
         id_next = id->next;
         /* NOTE: in case we delete a library, we also delete all its datablocks! */
         if ((id->tag & tag) || (id->lib != NULL && (id->lib->id.tag & tag))) {
           id->tag |= tag;
-          BKE_id_remapper_add(remapper, id, NULL);
-        }
-      }
 
-      if (BKE_id_remapper_is_empty(remapper)) {
-        continue;
+          /* Will tag 'never NULL' users of this ID too.
+           * Note that we cannot use BKE_libblock_unlink() here, since it would ignore indirect
+           * (and proxy!) links, this can lead to nasty crashing here in second,
+           * actual deleting loop.
+           * Also, this will also flag users of deleted data that cannot be unlinked
+           * (object using deleted obdata, etc.), so that they also get deleted. */
+          BKE_libblock_remap_locked(bmain,
+                                    id,
+                                    NULL,
+                                    (ID_REMAP_FLAG_NEVER_NULL_USAGE |
+                                     ID_REMAP_FORCE_NEVER_NULL_USAGE |
+                                     ID_REMAP_FORCE_INTERNAL_RUNTIME_POINTERS));
+        }
       }
-
-      /* Will tag 'never NULL' users of this ID too.
-       * Note that we cannot use BKE_libblock_unlink() here, since it would ignore indirect
-       * (and proxy!) links, this can lead to nasty crashing here in second,
-       * actual deleting loop.
-       * Also, this will also flag users of deleted data that cannot be unlinked
-       * (object using deleted obdata, etc.), so that they also get deleted. */
-      BKE_libblock_remap_multiple_locked(bmain,
-                                         remapper,
-                                         (ID_REMAP_FLAG_NEVER_NULL_USAGE |
-                                          ID_REMAP_FORCE_NEVER_NULL_USAGE |
-                                          ID_REMAP_FORCE_INTERNAL_RUNTIME_POINTERS));
     }
-    BKE_id_remapper_free(remapper);
   }
-
   BKE_main_unlock(bmain);
 
   /* In usual reversed order, such that all usage of a given ID, even 'never NULL' ones,
diff --git a/source/blender/blenkernel/intern/lib_id_remapper.cc b/source/blender/blenkernel/intern/lib_id_remapper.cc
deleted file mode 100644
index c1734c9826a..00000000000
--- a/source/blender/blenkernel/intern/lib_id_remapper.cc
+++ /dev/null
@@ -1,175 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2022 by Blender Foundation.
- */
-
-#include "DNA_ID.h"
-
-#include "BKE_idtype.h"
-#include "BKE_lib_id.h"
-#include "BKE_lib_remap.h"
-
-#include "MEM_guardedalloc.h"
-
-#include "BLI_map.hh"
-
-using IDTypeFilter = uint64_t;
-
-namespace blender::bke::id::remapper {
-struct IDRemapper {
- private:
-  Map<ID *, ID *> mappings;
-  IDTypeFilter source_types = 0;
-
- public:
-  void clear()
-  {
-    mappings.clear();
-    source_types = 0;
-  }
-
-  bool is_empty() const
-  {
-    return mappings.is_empty();
-  }
-
-  void add(ID *old_id, ID *new_id)
-  {
-    BLI_assert(old_id != nullptr);
-    BLI_assert(new_id == nullptr || (GS(old_id->name) == GS(new_id->name)));
-    mappings.add(old_id, new_id);
-    source_types |= BKE_idtype_idcode_to_idfilter(GS(old_id->name));
-  }
-
-  bool contains_mappings_for_any(IDTypeFilter filter) const
-  {
-    return (source_types & filter) != 0;
-  }
-
-  IDRemapperApplyResult apply(ID **r_id_ptr, IDRemapperApplyOptions options) const
-  {
-    BLI_assert(r_id_ptr != nullptr);
-    if (*r_id_ptr == nullptr) {
-      return ID_REMAP_RESULT_SOURCE_NOT_MAPPABLE;
-    }
-
-    if (!mappings.contains(*r_id_ptr)) {
-      return ID_REMAP_RESULT_SOURCE_UNAVAILABLE;
-    }
-
-    if (options & ID_REMAP_APPLY_UPDATE_REFCOUNT) {
-      id_us_min(*r_id_ptr);
-    }
-
-    *r_id_ptr = mappings.lookup(*r_id_ptr);
-    if (*r_id_ptr == nullptr) {
-      return ID_REMAP_RESULT_SOURCE_UNASSIGNED;
-    }
-
-    if (options & ID_REMAP_APPLY_UPDATE_REFCOUNT) {
-      id_us_plus(*r_id_ptr);
-    }
-
-    if (options & ID_REMAP_APPLY_ENSURE_REAL) {
-      id_us_ensure_real(*r_id_ptr);
-    }
-    return ID_REMAP_RESULT_SOURCE_REMAPPED;
-  }
-
-  void iter(IDRemapperIterFunction func, void *user_data) const
-  {
-    for (auto item : mappings.items()) {
-      func(item.key, item.value, user_data);
-    }
-  }
-};
-
-}  // namespace blender::bke::id::remapper
-
-/** \brief wrap CPP IDRemapper to a C handle. */
-static IDRemapper *wrap(blender::bke::id::remapper::IDRemapper *remapper)
-{
-  return static_cast<IDRemapper *>(static_cast<void *>(remapper));
-}
-
-/** \brief wrap C handle to a CPP IDRemapper. */
-static blender::bke::id::remapper::IDRemapper *unwrap(IDRemapper *remapper)
-{
-  return static_cast<blender::bke::id::remapper::IDRemapper *>(static_cast<void *>(remapper));
-}
-
-/** \brief wrap C handle to a CPP IDRemapper. */
-static const blender::bke::id::remapper::IDRemapper *unwrap(const IDRemapper *remapper)
-{
-  return static_cast<const blender::bke::id::remapper::IDRemapper *>(
-      static_cast<const void *>(remapper));
-}
-
-extern "C" {
-
-IDRemapper *BKE_id_remapper_create(void)
-{
-  blender::bke::id::remapper::IDRemapper *remapper =
-      MEM_new<blender::bke::id::remapper::IDRemapper>(__func__);
-  return wrap(remapper);
-}
-
-void BKE_id_remapper_free(IDRemapper *id_remapper)
-{
-  blender::bke::id::remapper::IDRemapper *remapper = unwrap(id_remapper);
-  MEM_delete<blender::bke::id::remapper::IDRemapper>(remapper);
-}
-
-void BKE_id_remapper_clear(struct IDRemapper *id_remapper)
-{
-  blender::bke::id::remapper::IDRemapper *remapper = unwrap(id_remapper);
-  remapper->clear();
-}
-
-bool BKE_id_remapper_is_empty(const struct IDRemapper *id_remapper)
-{
-  const blender::bke::id::remapper::IDRemapper *remapper = unwrap(id_remapper);
-  return remapper->is_empty();
-}
-
-void BKE_id_remapper_add(IDRemapper *id_remapper, ID *old_id, ID *new_id)
-{
-  blender::bke::id::remapper::IDRemapper *remapper = unwrap(id_remapper);
-  remapper->add(old_id, new_id);
-}
-
-bool BKE_id_remapper_has_mapping_for(const struct IDRemapper *id_remapper, uint64_t type_filter)
-{
-  const blender::bke::id::remapper::IDRemapper *remapper = unwrap(id_remapper);
-  return remapper->contains_mappings_for_any(type_filter);
-}
-
-IDRemapperApplyResult BKE_id_remapper_apply(const IDRemapper *id_remapper,
-                                            ID **r_id_ptr,
-                                            const IDRemapperApplyOptions options)
-{
-  const blender::bke::id::remapper::IDRemapper *remapper = unwrap(id_remapper);
-  return remapper->apply(r_id_ptr, options);
-}
-
-void BKE_id_remapper_iter(const struct IDRemapper *id_remapper,
-                          IDRemapperIterFunction func,
-                          void *user_data)
-{
-  const blender::bke::id::remapper::IDRemapper *remapper = unwrap(id_remapper);
-  remapper->iter(func, user_data);
-}
-}
diff --git a/source/blender/blenkernel/intern/lib_id_remapper_test.cc b/source/blender/blenkernel/intern/lib_id_remapper_test.cc
deleted file mode 100644
index 594f64dac73..00000000000
--- a/source/blender/blenkernel/intern/lib_id_remapper_test.cc
+++ /dev/null
@@ -1,83 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2022 by Blender Foundation.
- */
-
-#include "testing/testing.h"
-
-#include "BKE_lib_remap.h"
-
-#include "BLI_string.h"
-
-#include "DNA_ID.h"
-
-namespace blender::bke::id::remapper::tests {
-
-TEST(lib_id_remapper, unavailable)
-{
-  ID id1;
-  ID *idp = &id1;
-
-  IDRemapper *remapper = BKE_id_remapper_create();
-  IDRemapperApplyResult result = BKE_id_remapper_apply(remapper, &idp, ID_REMAP_APPLY_DEFAULT);
-  EXPECT_EQ(result, ID_REMAP_RESULT_SOURCE_UNAVAILABLE);
-
-  BKE_id_remapper_free(remapper);
-}
-
-TEST(lib_id_remapper, not_mappable)
-{
-  ID *idp = nullptr;
-
-  IDRemapper *remapper = BKE_id_remapper_create();
-  IDRemapperApplyResult result = BKE_id_remapper_apply(remapper, &idp, ID_REMAP_APPLY_DEFAULT);
-  EXPECT_EQ(result, ID_REMAP_RESULT_SOURCE_NOT_MAPPABLE);
-
-  BKE_id_remapper_free(remapper);
-}
-
-TEST(lib_id_remapper, mapped)
-{
-  ID id1;
-  ID id2;
-  ID *idp = &id1;
-  BLI_strncpy(id1.name, "OB1", sizeof(id1.name));
-  BLI_strncpy(id2.name, "OB2", sizeof(id2.name));
-
-  IDRemapper *remapper = BKE_id_remapper_create();
-  BKE_id_remapper_add(remapper, &id1, &id2);
-  IDRemapperApplyResult result = BKE_id_remapper_apply(remapper, &idp, ID_REMAP_APPLY_DEFAULT);
-  EXPECT_EQ(result, ID_REMAP_RESULT_SOURCE_REMAPPED);
-  EXPECT_EQ(idp, &id2);
-
-  BKE_id_remapper_free(remapper);
-}
-
-TEST(lib_id_remapper, unassigned)
-{
-  ID id1;
-  ID *idp = &id1;
-
-  IDRemapper *remapper = BKE_id_remapper_create();
-  BKE_id_remapper_add(remapper, &id1, nullptr);
-  IDRemapperApplyResult result = BKE_id_remapper_apply(remapper, &idp, ID_REMAP_APPLY_DEFAULT);
-  EXPECT_EQ(result, ID_REMAP_RESULT_SOURCE_UNASSIGNED);
-  EXPECT_EQ(idp, nullptr);
-
-  BKE_id_remapper_free(remapper);
-}
-
-}  // namespace blender::bke::id::remapper::tests
diff --git a/source/blender/blenkernel/intern/lib_override.c b/source/blender/blenkernel/intern/lib_override.c
index bc897e9075b..38ce8ea88b9 100644
--- a/source/blender/blenkernel/intern/lib_override.c
+++ b/source/blender/blenkernel/intern/lib_override.c
@@ -1121,45 +1121,6 @@ void BKE_lib_override_library_main_proxy_convert(Main *bmain, BlendFileReadRepor
   }
 }
 
-static void lib_override_library_remap(Main *bmain,
-                                       const ID *id_root_reference,
-                                       GHash *linkedref_to_old_override)
-{
-  ID *id;
-  struct IDRemapper *remapper = BKE_id_remapper_create();
-  FOREACH_MAIN_ID_BEGIN (bmain, id) {
-
-    if (id->tag & LIB_TAG_DOIT && id->newid != NULL && id->lib == id_root_reference->lib) {
-      ID *id_override_new = id->newid;
-      ID *id_override_old = BLI_ghash_lookup(linkedref_to_old_override, id);
-      if (id_override_old == NULL) {
-        continue;
-      }
-
-      BKE_id_remapper_add(remapper, id_override_old, id_override_new);
-      /* Remap no-main override IDs we just created too. */
-      GHashIterator linkedref_to_old_override_iter;
-      GHASH_ITER (linkedref_to_old_override_iter, linkedref_to_old_override) {
-        ID *id_override_old_iter = BLI_ghashIterator_getValue(&linkedref_to_old_override_iter);
-        if ((id_override_old_iter->tag & LIB_TAG_NO_MAIN) == 0) {
-          continue;
-        }
-
-        BKE_libblock_relink_ex(bmain,
-                               id_override_old_iter,
-                               id_override_old,
-                               id_override_new,
-                               ID_REMAP_FORCE_USER_REFCOUNT | ID_REMAP_FORCE_NEVER_NULL_USAGE);
-      }
-    }
-  }
-  FOREACH_MAIN_ID_END;
-
-  /* Remap all IDs to use the new override. */
-  BKE_libblock_remap_multiple(bmain, remapper, 0);
-  BKE_id_remapper_free(remapper);
-}
-
 static bool lib_override_library_resync(Main *bmain,
                                         Scene *scene,
                                         ViewLayer *view_layer,
@@ -1351,9 +1312,32 @@ static bool lib_override_library_resync(Main *bmain,
   }
   FOREACH_MAIN_LISTBASE_END;
 
-  /* We remap old to new override usages in a separate loop, after all new overrides have
+  /* We need to remap old to new override usages in a separate loop, after all new overrides have
    * been added to Main. */
-  lib_override_library_remap(bmain, id_root_reference, linkedref_to_old_override);
+  FOREACH_MAIN_ID_BEGIN (bmain, id) {
+    if (id->tag & LIB_TAG_DOIT && id->newid != NULL && id->lib == id_root_reference->lib) {
+      ID *id_override_new = id->newid;
+      ID *id_override_old = BLI_ghash_lookup(linkedref_to_old_override, id);
+
+      if (id_override_old != NULL) {
+        /* Remap all IDs to use the new override. */
+        BKE_libblock_remap(bmain, id_override_old, id_override_new, 0);
+        /* Remap no-main override IDs we just created too. */
+        GHashIterator linkedref_to_old_override_iter;
+        GHASH_ITER (linkedref_to_old_override_iter, linkedref_to_old_override) {
+          ID *id_override_old_iter = BLI_ghashIterator_getValue(&linkedref_to_old_override_iter);
+          if (id_override_old_iter->tag & LIB_TAG_NO_MAIN) {
+            BKE_libblock_relink_ex(bmain,
+                                   id_override_old_iter,
+                                   id_override_old,
+                                   id_override_new,
+                                   ID_REMAP_FORCE_USER_REFCOUNT | ID_REMAP_FORCE_NEVER_NULL_USAGE);
+          }
+        }
+      }
+    }
+  }
+  FOREACH_MAIN_ID_END;
 
   BKE_main_collection_sync(bmain);
 
diff --git a/source/blender/blenkernel/intern/lib_remap.c b/source/blender/blenkernel/intern/lib_remap.c
index c3ccedb9608..ec97ca83703 100644
--- a/source/blender/blenkernel/intern/lib_remap.c
+++ b/source/blender/blenkernel/intern/lib_remap.c
@@ -510,18 +510,11 @@ static void libblock_remap_data(
 #endif
 }
 
-typedef struct LibblockRemapMultipleUserData {
-  Main *bmain;
-  short remap_flags;
-} LibBlockRemapMultipleUserData;
-
-static void libblock_remap_foreach_idpair_cb(ID *old_id, ID *new_id, void *user_data)
+void BKE_libblock_remap_locked(Main *bmain, void *old_idv, void *new_idv, const short remap_flags)
 {
-  LibBlockRemapMultipleUserData *data = user_data;
-  Main *bmain = data->bmain;
-  const short remap_flags = data->remap_flags;
-
   IDRemap id_remap_data;
+  ID *old_id = old_idv;
+  ID *new_id = new_idv;
   int skipped_direct, skipped_refcounted;
 
   BLI_assert(old_id != NULL);
@@ -534,6 +527,13 @@ static void libblock_remap_foreach_idpair_cb(ID *old_id, ID *new_id, void *user_
     free_notifier_reference_cb(old_id);
   }
 
+  /* We assume editors do not hold references to their IDs... This is false in some cases
+   * (Image is especially tricky here),
+   * editors' code is to handle refcount (id->us) itself then. */
+  if (remap_editor_id_reference_cb) {
+    remap_editor_id_reference_cb(old_id, new_id);
+  }
+
   skipped_direct = id_remap_data.skipped_direct;
   skipped_refcounted = id_remap_data.skipped_refcounted;
 
@@ -606,41 +606,6 @@ static void libblock_remap_foreach_idpair_cb(ID *old_id, ID *new_id, void *user_
   DEG_relations_tag_update(bmain);
 }
 
-void BKE_libblock_remap_multiple_locked(Main *bmain,
-                                        const struct IDRemapper *mappings,
-                                        const short remap_flags)
-{
-  if (BKE_id_remapper_is_empty(mappings)) {
-    /* Early exit nothing to do. */
-    return;
-  }
-
-  LibBlockRemapMultipleUserData user_data;
-  user_data.bmain = bmain;
-  user_data.remap_flags = remap_flags;
-  BKE_id_remapper_iter(mappings, libblock_remap_foreach_idpair_cb, &user_data);
-
-  /* We assume editors do not hold references to their IDs... This is false in some cases
-   * (Image is especially tricky here),
-   * editors' code is to handle refcount (id->us) itself then. */
-  if (remap_editor_id_reference_cb) {
-    remap_editor_id_reference_cb(mappings);
-  }
-
-  /* Full rebuild of DEG! */
-  DEG_relations_tag_update(bmain);
-}
-
-void BKE_libblock_remap_locked(Main *bmain, void *old_idv, void *new_idv, const short remap_flags)
-{
-  struct IDRemapper *remapper = BKE_id_remapper_create();
-  ID *old_id = old_idv;
-  ID *new_id = new_idv;
-  BKE_id_remapper_add(remapper, old_id, new_id);
-  BKE_libblock_remap_multiple_locked(bmain, remapper, remap_flags);
-  BKE_id_remapper_free(remapper);
-}
-
 void BKE_libblock_remap(Main *bmain, void *old_idv, void *new_idv, const short remap_flags)
 {
   BKE_main_lock(bmain);
@@ -650,17 +615,6 @@ void BKE_libblock_remap(Main *bmain, void *old_idv, void *new_idv, const short r
   BKE_main_unlock(bmain);
 }
 
-void BKE_libblock_remap_multiple(Main *bmain,
-                                 const struct IDRemapper *mappings,
-                                 const short remap_flags)
-{
-  BKE_main_lock(bmain);
-
-  BKE_libblock_remap_multiple_locked(bmain, mappings, remap_flags);
-
-  BKE_main_unlock(bmain);
-}
-
 void BKE_libblock_unlink(Main *bmain,
                          void *idv,
                          const bool do_flag_never_null,
diff --git a/source/blender/editors/include/ED_util.h b/source/blender/editors/include/ED_util.h
index 4e794838b2f..6bcddfa631a 100644
--- a/source/blender/editors/include/ED_util.h
+++ b/source/blender/editors/include/ED_util.h
@@ -33,7 +33,6 @@ extern "C" {
 struct GPUBatch;
 struct Main;
 struct bContext;
-struct IDRemapper;
 
 /* ed_util.c */
 
@@ -61,13 +60,10 @@ bool ED_editors_flush_edits(struct Main *bmain);
  *
  * \param new_id: may be NULL to unlink \a old_id.
  */
-void ED_spacedata_id_remap_single(struct ScrArea *area,
-                               struct SpaceLink *sl,
-                               struct ID *old_id,
-                               struct ID *new_id);
 void ED_spacedata_id_remap(struct ScrArea *area,
                            struct SpaceLink *sl,
-                           const struct IDRemapper *mappings);
+                           struct ID *old_id,
+                           struct ID *new_id);
 
 void ED_operatortypes_edutils(void);
 
diff --git a/source/blender/editors/space_action/space_action.c b/source/blender/editors/space_action/space_action.c
index ba96ac52f1f..4463856f40a 100644
--- a/source/blender/editors/space_action/space_action.c
+++ b/source/blender/editors/space_action/space_action.c
@@ -36,7 +36,6 @@
 #include "BLI_utildefines.h"
 
 #include "BKE_context.h"
-#include "BKE_lib_remap.h"
 #include "BKE_nla.h"
 #include "BKE_screen.h"
 
@@ -815,15 +814,20 @@ static void action_refresh(const bContext *C, ScrArea *area)
   /* XXX re-sizing y-extents of tot should go here? */
 }
 
-static void action_id_remap(ScrArea *UNUSED(area),
-                            SpaceLink *slink,
-                            const struct IDRemapper *mappings)
+static void action_id_remap(ScrArea *UNUSED(area), SpaceLink *slink, ID *old_id, ID *new_id)
 {
   SpaceAction *sact = (SpaceAction *)slink;
 
-  BKE_id_remapper_apply(mappings, (ID **)&sact->action, ID_REMAP_APPLY_DEFAULT);
-  BKE_id_remapper_apply(mappings, (ID **)&sact->ads.filter_grp, ID_REMAP_APPLY_DEFAULT);
-  BKE_id_remapper_apply(mappings, &sact->ads.source, ID_REMAP_APPLY_DEFAULT);
+  if ((ID *)sact->action == old_id) {
+    sact->action = (bAction *)new_id;
+  }
+
+  if ((ID *)sact->ads.filter_grp == old_id) {
+    sact->ads.filter_grp = (Collection *)new_id;
+  }
+  if ((ID *)sact->ads.source == old_id) {
+    sact->ads.source = new_id;
+  }
 }
 
 /**
diff --git a/source/blender/editors/space_buttons/space_buttons.c b/source/blender/editors/space_buttons/space_buttons.c
index cf1e7788ff8..007a9105c76 100644
--- a/source/blender/editors/space_buttons/space_buttons.c
+++ b/source/blender/editors/space_buttons/space_buttons.c
@@ -32,7 +32,6 @@
 
 #include "BKE_context.h"
 #include "BKE_gpencil_modifier.h" /* Types for registering panels. */
-#include "BKE_lib_remap.h"
 #include "BKE_modifier.h"
 #include "BKE_screen.h"
 #include "BKE_shader_fx.h"
@@ -861,53 +860,54 @@ static void buttons_area_listener(const wmSpaceTypeListenerParams *params)
   }
 }
 
-static void buttons_id_remap(ScrArea *UNUSED(area),
-                             SpaceLink *slink,
-                             const struct IDRemapper *mappings)
+static void buttons_id_remap(ScrArea *UNUSED(area), SpaceLink *slink, ID *old_id, ID *new_id)
 {
   SpaceProperties *sbuts = (SpaceProperties *)slink;
 
-  if (BKE_id_remapper_apply(mappings, &sbuts->pinid, ID_REMAP_APPLY_DEFAULT) ==
-      ID_REMAP_RESULT_SOURCE_UNASSIGNED) {
-    sbuts->flag &= ~SB_PIN_CONTEXT;
+  if (sbuts->pinid == old_id) {
+    sbuts->pinid = new_id;
+    if (new_id == NULL) {
+      sbuts->flag &= ~SB_PIN_CONTEXT;
+    }
   }
 
   if (sbuts->path) {
     ButsContextPath *path = sbuts->path;
-    for (int i = 0; i < path->len; i++) {
-      switch (BKE_id_remapper_apply(mappings, &path->ptr[i].owner_id, ID_REMAP_APPLY_DEFAULT)) {
-        case ID_REMAP_RESULT_SOURCE_UNASSIGNED: {
-          if (i == 0) {
-            MEM_SAFE_FREE(sbuts->path);
-          }
-          else {
-            memset(&path->ptr[i], 0, sizeof(path->ptr[i]) * (path->len - i));
-            path->len = i;
-          }
-          break;
-        }
-        case ID_REMAP_RESULT_SOURCE_REMAPPED: {
-          RNA_id_pointer_create(path->ptr[i].owner_id, &path->ptr[i]);
-          /* There is no easy way to check/make path downwards valid, just nullify it.
-           * Next redraw will rebuild this anyway. */
-          i++;
-          memset(&path->ptr[i], 0, sizeof(path->ptr[i]) * (path->len - i));
-          path->len = i;
-          break;
-        }
 
-        case ID_REMAP_RESULT_SOURCE_NOT_MAPPABLE:
-        case ID_REMAP_RESULT_SOURCE_UNAVAILABLE: {
-          /* Nothing to do. */
-          break;
-        }
+    int i;
+    for (i = 0; i < path->len; i++) {
+      if (path->ptr[i].owner_id == old_id) {
+        break;
+      }
+    }
+
+    if (i == path->len) {
+      /* pass */
+    }
+    else if (new_id == NULL) {
+      if (i == 0) {
+        MEM_SAFE_FREE(sbuts->path);
+      }
+      else {
+        memset(&path->ptr[i], 0, sizeof(path->ptr[i]) * (path->len - i));
+        path->len = i;
       }
     }
+    else {
+      RNA_id_pointer_create(new_id, &path->ptr[i]);
+      /* There is no easy way to check/make path downwards valid, just nullify it.
+       * Next redraw will rebuild this anyway. */
+      i++;
+      memset(&path->ptr[i], 0, sizeof(path->ptr[i]) * (path->len - i));
+      path->len = i;
+    }
   }
 
   if (sbuts->texuser) {
     ButsContextTexture *ct = sbuts->texuser;
-    BKE_id_remapper_apply(mappings, (ID **)&ct->texture, ID_REMAP_APPLY_DEFAULT);
+    if ((ID *)ct->texture == old_id) {
+      ct->texture = (Tex *)new_id;
+    }
     BLI_freelistN(&ct->users);
     ct->user = NULL;
   }
diff --git a/source/blender/editors/space_clip/space_clip.c b/source/blender/editors/space_clip/space_clip.c
index da1d2dea653..b6dbda79a2d 100644
--- a/source/blender/editors/space_clip/space_clip.c
+++ b/source/blender/editors/space_clip/space_clip.c
@@ -39,7 +39,6 @@
 
 #include "BKE_context.h"
 #include "BKE_lib_id.h"
-#include "BKE_lib_remap.h"
 #include "BKE_movieclip.h"
 #include "BKE_screen.h"
 #include "BKE_tracking.h"
@@ -1318,18 +1317,23 @@ static void clip_properties_region_listener(const wmRegionListenerParams *params
 
 /********************* registration ********************/
 
-static void clip_id_remap(ScrArea *UNUSED(area),
-                          SpaceLink *slink,
-                          const struct IDRemapper *mappings)
+static void clip_id_remap(ScrArea *UNUSED(area), SpaceLink *slink, ID *old_id, ID *new_id)
 {
   SpaceClip *sclip = (SpaceClip *)slink;
 
-  if (!BKE_id_remapper_has_mapping_for(mappings, FILTER_ID_MC | FILTER_ID_MSK)) {
+  if (!ELEM(GS(old_id->name), ID_MC, ID_MSK)) {
     return;
   }
 
-  BKE_id_remapper_apply(mappings, (ID **)&sclip->clip, ID_REMAP_APPLY_ENSURE_REAL);
-  BKE_id_remapper_apply(mappings, (ID **)&sclip->mask_info.mask, ID_REMAP_APPLY_ENSURE_REAL);
+  if ((ID *)sclip->clip == old_id) {
+    sclip->clip = (MovieClip *)new_id;
+    id_us_ensure_real(new_id);
+  }
+
+  if ((ID *)sclip->mask_info.mask == old_id) {
+    sclip->mask_info.mask = (Mask *)new_id;
+    id_us_ensure_real(new_id);
+  }
 }
 
 void ED_spacetype_clip(void)
diff --git a/source/blender/editors/space_file/space_file.c b/source/blender/editors/space_file/space_file.c
index 470128f61bd..97a5f173ffd 100644
--- a/source/blender/editors/space_file/space_file.c
+++ b/source/blender/editors/space_file/space_file.c
@@ -33,7 +33,6 @@
 #include "BKE_appdir.h"
 #include "BKE_context.h"
 #include "BKE_global.h"
-#include "BKE_lib_remap.h"
 #include "BKE_main.h"
 #include "BKE_screen.h"
 
@@ -990,7 +989,7 @@ static int /*eContextResult*/ file_context(const bContext *C,
   return CTX_RESULT_MEMBER_NOT_FOUND;
 }
 
-static void file_id_remap(ScrArea *area, SpaceLink *sl, const struct IDRemapper *UNUSED(mappings))
+static void file_id_remap(ScrArea *area, SpaceLink *sl, ID *UNUSED(old_id), ID *UNUSED(new_id))
 {
   SpaceFile *sfile = (SpaceFile *)sl;
 
diff --git a/source/blender/editors/space_graph/space_graph.c b/source/blender/editors/space_graph/space_graph.c
index 7d5e8836490..40c95d4f382 100644
--- a/source/blender/editors/space_graph/space_graph.c
+++ b/source/blender/editors/space_graph/space_graph.c
@@ -36,7 +36,6 @@
 
 #include "BKE_context.h"
 #include "BKE_fcurve.h"
-#include "BKE_lib_remap.h"
 #include "BKE_screen.h"
 
 #include "ED_anim_api.h"
@@ -797,17 +796,18 @@ static void graph_refresh(const bContext *C, ScrArea *area)
   graph_refresh_fcurve_colors(C);
 }
 
-static void graph_id_remap(ScrArea *UNUSED(area),
-                           SpaceLink *slink,
-                           const struct IDRemapper *mappings)
+static void graph_id_remap(ScrArea *UNUSED(area), SpaceLink *slink, ID *old_id, ID *new_id)
 {
   SpaceGraph *sgraph = (SpaceGraph *)slink;
-  if (!sgraph->ads) {
-    return;
-  }
 
-  BKE_id_remapper_apply(mappings, (ID **)&sgraph->ads->filter_grp, ID_REMAP_APPLY_DEFAULT);
-  BKE_id_remapper_apply(mappings, (ID **)&sgraph->ads->source, ID_REMAP_APPLY_DEFAULT);
+  if (sgraph->ads) {
+    if ((ID *)sgraph->ads->filter_grp == old_id) {
+      sgraph->ads->filter_grp = (Collection *)new_id;
+    }
+    if ((ID *)sgraph->ads->source == old_id) {
+      sgraph->ads->source = new_id;
+    }
+  }
 }
 
 static int graph_space_subtype_get(ScrArea *area)
diff --git a/source/blender/editors/space_image/space_image.c b/source/blender/editors/space_image/space_image.c
index eb5b6104a79..52cb36b1b8f 100644
--- a/source/blender/editors/space_image/space_image.c
+++ b/source/blender/editors/space_image/space_image.c
@@ -37,7 +37,6 @@
 #include "BKE_context.h"
 #include "BKE_image.h"
 #include "BKE_lib_id.h"
-#include "BKE_lib_remap.h"
 #include "BKE_screen.h"
 
 #include "RNA_access.h"
@@ -984,19 +983,29 @@ static void image_header_region_listener(const wmRegionListenerParams *params)
   }
 }
 
-static void image_id_remap(ScrArea *UNUSED(area),
-                           SpaceLink *slink,
-                           const struct IDRemapper *mappings)
+static void image_id_remap(ScrArea *UNUSED(area), SpaceLink *slink, ID *old_id, ID *new_id)
 {
   SpaceImage *simg = (SpaceImage *)slink;
 
-  if (!BKE_id_remapper_has_mapping_for(mappings, FILTER_ID_IM | FILTER_ID_GD | FILTER_ID_MSK)) {
+  if (!ELEM(GS(old_id->name), ID_IM, ID_GD, ID_MSK)) {
     return;
   }
 
-  BKE_id_remapper_apply(mappings, (ID **)&simg->image, ID_REMAP_APPLY_ENSURE_REAL);
-  BKE_id_remapper_apply(mappings, (ID **)&simg->gpd, ID_REMAP_APPLY_UPDATE_REFCOUNT);
-  BKE_id_remapper_apply(mappings, (ID **)&simg->mask_info.mask, ID_REMAP_APPLY_ENSURE_REAL);
+  if ((ID *)simg->image == old_id) {
+    simg->image = (Image *)new_id;
+    id_us_ensure_real(new_id);
+  }
+
+  if ((ID *)simg->gpd == old_id) {
+    simg->gpd = (bGPdata *)new_id;
+    id_us_min(old_id);
+    id_us_plus(new_id);
+  }
+
+  if ((ID *)simg->mask_info.mask == old_id) {
+    simg->mask_info.mask = (Mask *)new_id;
+    id_us_ensure_real(new_id);
+  }
 }
 
 /**
diff --git a/source/blender/editors/space_nla/space_nla.c b/source/blender/editors/space_nla/space_nla.c
index 962b5151661..0771153c5f5 100644
--- a/source/blender/editors/space_nla/space_nla.c
+++ b/source/blender/editors/space_nla/space_nla.c
@@ -33,7 +33,6 @@
 #include "BLI_utildefines.h"
 
 #include "BKE_context.h"
-#include "BKE_lib_remap.h"
 #include "BKE_screen.h"
 
 #include "ED_anim_api.h"
@@ -578,17 +577,18 @@ static void nla_listener(const wmSpaceTypeListenerParams *params)
   }
 }
 
-static void nla_id_remap(ScrArea *UNUSED(area),
-                         SpaceLink *slink,
-                         const struct IDRemapper *mappings)
+static void nla_id_remap(ScrArea *UNUSED(area), SpaceLink *slink, ID *old_id, ID *new_id)
 {
   SpaceNla *snla = (SpaceNla *)slink;
 
-  if (snla->ads == NULL) {
-    return;
+  if (snla->ads) {
+    if ((ID *)snla->ads->filter_grp == old_id) {
+      snla->ads->filter_grp = (Collection *)new_id;
+    }
+    if ((ID *)snla->ads->source == old_id) {
+      snla->ads->source = new_id;
+    }
   }
-  BKE_id_remapper_apply(mappings, (ID **)&snla->ads->filter_grp, ID_REMAP_APPLY_DEFAULT);
-  BKE_id_remapper_apply(mappings, (ID **)&snla->ads->source, ID_REMAP_APPLY_DEFAULT);
 }
 
 void ED_spacetype_nla(void)
diff --git a/source/blender/editors/space_node/space_node.cc b/source/blender/editors/space_node/space_node.cc
index 8f465ffbf80..f794a8ce294 100644
--- a/source/blender/editors/space_node/space_node.cc
+++ b/source/blender/editors/space_node/space_node.cc
@@ -31,7 +31,6 @@
 
 #include "BKE_context.h"
 #include "BKE_lib_id.h"
-#include "BKE_lib_remap.h"
 #include "BKE_node.h"
 #include "BKE_screen.h"
 
@@ -897,63 +896,71 @@ static void node_widgets()
   WM_gizmogrouptype_append_and_link(gzmap_type, NODE_GGT_backdrop_corner_pin);
 }
 
-static void node_id_remap(ScrArea *UNUSED(area),
-                          SpaceLink *slink,
-                          const struct IDRemapper *mappings)
+static void node_id_remap(ScrArea *UNUSED(area), SpaceLink *slink, ID *old_id, ID *new_id)
 {
   SpaceNode *snode = (SpaceNode *)slink;
 
-  if (ELEM(BKE_id_remapper_apply(mappings, &snode->id, ID_REMAP_APPLY_DEFAULT),
-           ID_REMAP_RESULT_SOURCE_REMAPPED,
-           ID_REMAP_RESULT_SOURCE_UNASSIGNED)) {
+  if (snode->id == old_id) {
     /* nasty DNA logic for SpaceNode:
      * ideally should be handled by editor code, but would be bad level call
      */
     BLI_freelistN(&snode->treepath);
 
     /* XXX Untested in case new_id != nullptr... */
+    snode->id = new_id;
     snode->from = nullptr;
     snode->nodetree = nullptr;
     snode->edittree = nullptr;
   }
-  if (BKE_id_remapper_apply(mappings, &snode->from, ID_REMAP_APPLY_DEFAULT) ==
-      ID_REMAP_RESULT_SOURCE_UNASSIGNED) {
-    snode->flag &= ~SNODE_PIN;
+  else if (GS(old_id->name) == ID_OB) {
+    if (snode->from == old_id) {
+      if (new_id == nullptr) {
+        snode->flag &= ~SNODE_PIN;
+      }
+      snode->from = new_id;
+    }
   }
-  BKE_id_remapper_apply(mappings, (ID **)&snode->gpd, ID_REMAP_APPLY_UPDATE_REFCOUNT);
-
-  if (!BKE_id_remapper_has_mapping_for(mappings, FILTER_ID_NT)) {
-    return;
+  else if (GS(old_id->name) == ID_GD) {
+    if ((ID *)snode->gpd == old_id) {
+      snode->gpd = (bGPdata *)new_id;
+      id_us_min(old_id);
+      id_us_plus(new_id);
+    }
   }
+  else if (GS(old_id->name) == ID_NT) {
+    bNodeTreePath *path, *path_next;
 
-  bNodeTreePath *path, *path_next;
-  for (path = (bNodeTreePath *)snode->treepath.first; path; path = path->next) {
-    BKE_id_remapper_apply(mappings, (ID **)&path->nodetree, ID_REMAP_APPLY_ENSURE_REAL);
-    if (path == snode->treepath.first) {
-      /* first nodetree in path is same as snode->nodetree */
-      snode->nodetree = path->nodetree;
-    }
-    if (path->nodetree == nullptr) {
-      break;
+    for (path = (bNodeTreePath *)snode->treepath.first; path; path = path->next) {
+      if ((ID *)path->nodetree == old_id) {
+        path->nodetree = (bNodeTree *)new_id;
+        id_us_ensure_real(new_id);
+      }
+      if (path == snode->treepath.first) {
+        /* first nodetree in path is same as snode->nodetree */
+        snode->nodetree = path->nodetree;
+      }
+      if (path->nodetree == nullptr) {
+        break;
+      }
     }
-  }
 
-  /* remaining path entries are invalid, remove */
-  for (; path; path = path_next) {
-    path_next = path->next;
+    /* remaining path entries are invalid, remove */
+    for (; path; path = path_next) {
+      path_next = path->next;
 
-    BLI_remlink(&snode->treepath, path);
-    MEM_freeN(path);
-  }
+      BLI_remlink(&snode->treepath, path);
+      MEM_freeN(path);
+    }
 
-  /* edittree is just the last in the path,
-   * set this directly since the path may have been shortened above */
-  if (snode->treepath.last) {
-    path = (bNodeTreePath *)snode->treepath.last;
-    snode->edittree = path->nodetree;
-  }
-  else {
-    snode->edittree = nullptr;
+    /* edittree is just the last in the path,
+     * set this directly since the path may have been shortened above */
+    if (snode->treepath.last) {
+      path = (bNodeTreePath *)snode->treepath.last;
+      snode->edittree = path->nodetree;
+    }
+    else {
+      snode->edittree = nullptr;
+    }
   }
 }
 
diff --git a/source/blender/editors/space_outliner/space_outliner.cc b/source/blender/editors/space_outliner/space_outliner.cc
index 0fb17fa3f47..bb4e57a79da 100644
--- a/source/blender/editors/space_outliner/space_outliner.cc
+++ b/source/blender/editors/space_outliner/space_outliner.cc
@@ -31,7 +31,6 @@
 #include "BLI_utildefines.h"
 
 #include "BKE_context.h"
-#include "BKE_lib_remap.h"
 #include "BKE_outliner_treehash.h"
 #include "BKE_screen.h"
 
@@ -406,49 +405,45 @@ static SpaceLink *outliner_duplicate(SpaceLink *sl)
   return (SpaceLink *)space_outliner_new;
 }
 
-static void outliner_id_remap(ScrArea *area, SpaceLink *slink, const struct IDRemapper *mappings)
+static void outliner_id_remap(ScrArea *area, SpaceLink *slink, ID *old_id, ID *new_id)
 {
   SpaceOutliner *space_outliner = (SpaceOutliner *)slink;
 
-  BKE_id_remapper_apply(mappings, (ID **)&space_outliner->search_tse.id, ID_REMAP_APPLY_DEFAULT);
-
-  if (!space_outliner->treestore) {
-    return;
+  /* Some early out checks. */
+  if (!TREESTORE_ID_TYPE(old_id)) {
+    return; /* ID type is not used by outliner. */
   }
 
-  TreeStoreElem *tselem;
-  BLI_mempool_iter iter;
-  bool changed = false;
-  bool unassigned = false;
+  if (space_outliner->search_tse.id == old_id) {
+    space_outliner->search_tse.id = new_id;
+  }
 
-  BLI_mempool_iternew(space_outliner->treestore, &iter);
-  while ((tselem = static_cast<TreeStoreElem *>(BLI_mempool_iterstep(&iter)))) {
-    switch (BKE_id_remapper_apply(mappings, &tselem->id, ID_REMAP_APPLY_DEFAULT)) {
-      case ID_REMAP_RESULT_SOURCE_REMAPPED:
-        changed = true;
-        break;
-      case ID_REMAP_RESULT_SOURCE_UNASSIGNED:
+  if (space_outliner->treestore) {
+    TreeStoreElem *tselem;
+    BLI_mempool_iter iter;
+    bool changed = false;
+
+    BLI_mempool_iternew(space_outliner->treestore, &iter);
+    while ((tselem = static_cast<TreeStoreElem *>(BLI_mempool_iterstep(&iter)))) {
+      if (tselem->id == old_id) {
+        tselem->id = new_id;
         changed = true;
-        unassigned = true;
-        break;
-      case ID_REMAP_RESULT_SOURCE_UNAVAILABLE:
-      case ID_REMAP_RESULT_SOURCE_NOT_MAPPABLE:
-        break;
+      }
     }
-  }
 
-  /* Note that the Outliner may not be the active editor of the area, and hence not initialized.
-   * So runtime data might not have been created yet. */
-  if (space_outliner->runtime && space_outliner->runtime->treehash && changed) {
-    /* rebuild hash table, because it depends on ids too */
-    /* postpone a full rebuild because this can be called many times on-free */
-    space_outliner->storeflag |= SO_TREESTORE_REBUILD;
-
-    if (unassigned) {
-      /* Redraw is needed when removing data for multiple outlines show the same data.
-       * without this, the stale data won't get fully flushed when this outliner
-       * is not the active outliner the user is interacting with. See T85976. */
-      ED_area_tag_redraw(area);
+    /* Note that the Outliner may not be the active editor of the area, and hence not initialized.
+     * So runtime data might not have been created yet. */
+    if (space_outliner->runtime && space_outliner->runtime->treehash && changed) {
+      /* rebuild hash table, because it depends on ids too */
+      /* postpone a full rebuild because this can be called many times on-free */
+      space_outliner->storeflag |= SO_TREESTORE_REBUILD;
+
+      if (new_id == nullptr) {
+        /* Redraw is needed when removing data for multiple outlines show the same data.
+         * without this, the stale data won't get fully flushed when this outliner
+         * is not the active outliner the user is interacting with. See T85976. */
+        ED_area_tag_redraw(area);
+      }
     }
   }
 }
diff --git a/source/blender/editors/space_sequencer/space_sequencer.c b/source/blender/editors/space_sequencer/space_sequencer.c
index b294fdf4820..b93f421ff5c 100644
--- a/source/blender/editors/space_sequencer/space_sequencer.c
+++ b/source/blender/editors/space_sequencer/space_sequencer.c
@@ -39,7 +39,6 @@
 #include "BKE_context.h"
 #include "BKE_global.h"
 #include "BKE_lib_id.h"
-#include "BKE_lib_remap.h"
 #include "BKE_screen.h"
 #include "BKE_sequencer_offscreen.h"
 
@@ -989,12 +988,19 @@ static void sequencer_buttons_region_listener(const wmRegionListenerParams *para
   }
 }
 
-static void sequencer_id_remap(ScrArea *UNUSED(area),
-                               SpaceLink *slink,
-                               const struct IDRemapper *mappings)
+static void sequencer_id_remap(ScrArea *UNUSED(area), SpaceLink *slink, ID *old_id, ID *new_id)
 {
   SpaceSeq *sseq = (SpaceSeq *)slink;
-  BKE_id_remapper_apply(mappings, (ID **)&sseq->gpd, ID_REMAP_APPLY_DEFAULT);
+
+  if (!ELEM(GS(old_id->name), ID_GD)) {
+    return;
+  }
+
+  if ((ID *)sseq->gpd == old_id) {
+    sseq->gpd = (bGPdata *)new_id;
+    id_us_min(old_id);
+    id_us_plus(new_id);
+  }
 }
 
 /* ************************************* */
diff --git a/source/blender/editors/space_spreadsheet/space_spreadsheet.cc b/source/blender/editors/space_spreadsheet/space_spreadsheet.cc
index 18f383d45fb..02f7f1d71c4 100644
--- a/source/blender/editors/space_spreadsheet/space_spreadsheet.cc
+++ b/source/blender/editors/space_spreadsheet/space_spreadsheet.cc
@@ -18,7 +18,6 @@
 
 #include "BLI_listbase.h"
 
-#include "BKE_lib_remap.h"
 #include "BKE_screen.h"
 
 #include "ED_screen.h"
@@ -172,23 +171,21 @@ static void spreadsheet_keymap(wmKeyConfig *keyconf)
   WM_keymap_ensure(keyconf, "Spreadsheet Generic", SPACE_SPREADSHEET, 0);
 }
 
-static void spreadsheet_id_remap(ScrArea *UNUSED(area),
-                                 SpaceLink *slink,
-                                 const IDRemapper *mappings)
+static void spreadsheet_id_remap(ScrArea *UNUSED(area), SpaceLink *slink, ID *old_id, ID *new_id)
 {
   SpaceSpreadsheet *sspreadsheet = (SpaceSpreadsheet *)slink;
   LISTBASE_FOREACH (SpreadsheetContext *, context, &sspreadsheet->context_path) {
-    if (context->type != SPREADSHEET_CONTEXT_OBJECT) {
-      continue;
-    }
-    SpreadsheetContextObject *object_context = (SpreadsheetContextObject *)context;
-
-    if (object_context->object != nullptr && GS(object_context->object->id.name) != ID_OB) {
-      object_context->object = nullptr;
-      continue;
+    if (context->type == SPREADSHEET_CONTEXT_OBJECT) {
+      SpreadsheetContextObject *object_context = (SpreadsheetContextObject *)context;
+      if ((ID *)object_context->object == old_id) {
+        if (new_id && GS(new_id->name) == ID_OB) {
+          object_context->object = (Object *)new_id;
+        }
+        else {
+          object_context->object = nullptr;
+        }
+      }
     }
-
-    BKE_id_remapper_apply(mappings, ((ID **)&object_context->object), ID_REMAP_APPLY_DEFAULT);
   }
 }
 
diff --git a/source/blender/editors/space_text/space_text.c b/source/blender/editors/space_text/space_text.c
index 7339d8248c8..f449ce50ae3 100644
--- a/source/blender/editors/space_text/space_text.c
+++ b/source/blender/editors/space_text/space_text.c
@@ -32,7 +32,6 @@
 #include "BKE_context.h"
 #include "BKE_global.h"
 #include "BKE_lib_id.h"
-#include "BKE_lib_remap.h"
 #include "BKE_screen.h"
 
 #include "ED_screen.h"
@@ -402,12 +401,18 @@ static void text_properties_region_draw(const bContext *C, ARegion *region)
   }
 }
 
-static void text_id_remap(ScrArea *UNUSED(area),
-                          SpaceLink *slink,
-                          const struct IDRemapper *mappings)
+static void text_id_remap(ScrArea *UNUSED(area), SpaceLink *slink, ID *old_id, ID *new_id)
 {
   SpaceText *stext = (SpaceText *)slink;
-  BKE_id_remapper_apply(mappings, (ID **)&stext->text, ID_REMAP_APPLY_ENSURE_REAL);
+
+  if (!ELEM(GS(old_id->name), ID_TXT)) {
+    return;
+  }
+
+  if ((ID *)stext->text == old_id) {
+    stext->text = (Text *)new_id;
+    id_us_ensure_real(new_id);
+  }
 }
 
 /********************* registration ********************/
diff --git a/source/blender/editors/space_view3d/space_view3d.c b/source/blender/editors/space_view3d/space_view3d.c
index 0a5bebac8a8..8822ea6af3b 100644
--- a/source/blender/editors/space_view3d/space_view3d.c
+++ b/source/blender/editors/space_view3d/space_view3d.c
@@ -48,7 +48,6 @@
 #include "BKE_idprop.h"
 #include "BKE_lattice.h"
 #include "BKE_layer.h"
-#include "BKE_lib_remap.h"
 #include "BKE_main.h"
 #include "BKE_mball.h"
 #include "BKE_mesh.h"
@@ -1814,54 +1813,50 @@ static int view3d_context(const bContext *C, const char *member, bContextDataRes
   return CTX_RESULT_MEMBER_NOT_FOUND;
 }
 
-static void view3d_id_remap_v3d_ob_centers(View3D *v3d, const struct IDRemapper *mappings)
+static void view3d_id_remap(ScrArea *area, SpaceLink *slink, ID *old_id, ID *new_id)
 {
-  if (BKE_id_remapper_apply(mappings, (ID **)&v3d->ob_center, ID_REMAP_APPLY_DEFAULT) ==
-      ID_REMAP_RESULT_SOURCE_UNASSIGNED) {
-    /* Otherwise, bonename may remain valid...
-     * We could be smart and check this, too? */
-    v3d->ob_center_bone[0] = '\0';
+  View3D *v3d;
+  ARegion *region;
+  bool is_local = false;
+
+  if (!ELEM(GS(old_id->name), ID_OB, ID_MA, ID_IM, ID_MC)) {
+    return;
   }
-}
 
-static void view3d_id_remap_v3d(ScrArea *area,
-                                SpaceLink *slink,
-                                View3D *v3d,
-                                const struct IDRemapper *mappings,
-                                const bool is_local)
-{
-  ARegion *region;
-  if (BKE_id_remapper_apply(mappings, (ID **)&v3d->camera, ID_REMAP_APPLY_DEFAULT) ==
-      ID_REMAP_RESULT_SOURCE_UNASSIGNED) {
-    /* 3D view might be inactive, in that case needs to use slink->regionbase */
-    ListBase *regionbase = (slink == area->spacedata.first) ? &area->regionbase :
-                                                              &slink->regionbase;
-    for (region = regionbase->first; region; region = region->next) {
-      if (region->regiontype == RGN_TYPE_WINDOW) {
-        RegionView3D *rv3d = is_local ? ((RegionView3D *)region->regiondata)->localvd :
-                                        region->regiondata;
-        if (rv3d && (rv3d->persp == RV3D_CAMOB)) {
-          rv3d->persp = RV3D_PERSP;
+  for (v3d = (View3D *)slink; v3d; v3d = v3d->localvd, is_local = true) {
+    if ((ID *)v3d->camera == old_id) {
+      v3d->camera = (Object *)new_id;
+      if (!new_id) {
+        /* 3D view might be inactive, in that case needs to use slink->regionbase */
+        ListBase *regionbase = (slink == area->spacedata.first) ? &area->regionbase :
+                                                                  &slink->regionbase;
+        for (region = regionbase->first; region; region = region->next) {
+          if (region->regiontype == RGN_TYPE_WINDOW) {
+            RegionView3D *rv3d = is_local ? ((RegionView3D *)region->regiondata)->localvd :
+                                            region->regiondata;
+            if (rv3d && (rv3d->persp == RV3D_CAMOB)) {
+              rv3d->persp = RV3D_PERSP;
+            }
+          }
         }
       }
     }
-  }
-}
-
-static void view3d_id_remap(ScrArea *area, SpaceLink *slink, const struct IDRemapper *mappings)
-{
 
-  if (!BKE_id_remapper_has_mapping_for(
-          mappings, FILTER_ID_OB | FILTER_ID_MA | FILTER_ID_IM | FILTER_ID_MC)) {
-    return;
-  }
+    /* Values in local-view aren't used, see: T52663 */
+    if (is_local == false) {
+      if ((ID *)v3d->ob_center == old_id) {
+        v3d->ob_center = (Object *)new_id;
+        /* Otherwise, bonename may remain valid...
+         * We could be smart and check this, too? */
+        if (new_id == NULL) {
+          v3d->ob_center_bone[0] = '\0';
+        }
+      }
+    }
 
-  View3D *view3d = (View3D *)slink;
-  view3d_id_remap_v3d(area, slink, view3d, mappings, false);
-  view3d_id_remap_v3d_ob_centers(view3d, mappings);
-  if (view3d->localvd != NULL) {
-    /* Object centers in local-view aren't used, see: T52663 */
-    view3d_id_remap_v3d(area, slink, view3d->localvd, mappings, true);
+    if (is_local) {
+      break;
+    }
   }
 }
 
diff --git a/source/blender/editors/util/ed_util.c b/source/blender/editors/util/ed_util.c
index 0320a2a9a1a..882f140c063 100644
--- a/source/blender/editors/util/ed_util.c
+++ b/source/blender/editors/util/ed_util.c
@@ -35,7 +35,6 @@
 
 #include "BKE_collection.h"
 #include "BKE_global.h"
-#include "BKE_lib_remap.h"
 #include "BKE_main.h"
 #include "BKE_material.h"
 #include "BKE_multires.h"
@@ -435,27 +434,11 @@ void unpack_menu(bContext *C,
   UI_popup_menu_end(C, pup);
 }
 
-void ED_spacedata_id_remap(struct ScrArea *area,
-                           struct SpaceLink *sl,
-                           const struct IDRemapper *mappings)
-{
-  SpaceType *st = BKE_spacetype_from_id(sl->spacetype);
-  if (st && st->id_remap) {
-    st->id_remap(area, sl, mappings);
-  }
-}
-
-void ED_spacedata_id_remap_single(struct ScrArea *area,
-                                  struct SpaceLink *sl,
-                                  ID *old_id,
-                                  ID *new_id)
+void ED_spacedata_id_remap(struct ScrArea *area, struct SpaceLink *sl, ID *old_id, ID *new_id)
 {
   SpaceType *st = BKE_spacetype_from_id(sl->spacetype);
 
   if (st && st->id_remap) {
-    struct IDRemapper *mappings = BKE_id_remapper_create();
-    BKE_id_remapper_add(mappings, old_id, new_id);
-    st->id_remap(area, sl, mappings);
-    BKE_id_remapper_free(mappings);
+    st->id_remap(area, sl, old_id, new_id);
   }
 }
diff --git a/source/blender/windowmanager/WM_api.h b/source/blender/windowmanager/WM_api.h
index ff3e1b7474c..9e4d8e733a6 100644
--- a/source/blender/windowmanager/WM_api.h
+++ b/source/blender/windowmanager/WM_api.h
@@ -47,7 +47,6 @@ struct GHashIterator;
 struct GPUViewport;
 struct ID;
 struct IDProperty;
-struct IDRemapper;
 struct ImBuf;
 struct ImageFormatData;
 struct Main;
@@ -472,7 +471,7 @@ void WM_main_add_notifier(unsigned int type, void *reference);
  * Clear notifiers by reference, Used so listeners don't act on freed data.
  */
 void WM_main_remove_notifier_reference(const void *reference);
-void WM_main_remap_editor_id_reference(const struct IDRemapper *mappings);
+void WM_main_remap_editor_id_reference(struct ID *old_id, struct ID *new_id);
 
 /* reports */
 /**
diff --git a/source/blender/windowmanager/intern/wm_event_system.c b/source/blender/windowmanager/intern/wm_event_system.c
index 3e30c06ade2..28d8413fe0b 100644
--- a/source/blender/windowmanager/intern/wm_event_system.c
+++ b/source/blender/windowmanager/intern/wm_event_system.c
@@ -51,7 +51,6 @@
 #include "BKE_customdata.h"
 #include "BKE_global.h"
 #include "BKE_idprop.h"
-#include "BKE_lib_remap.h"
 #include "BKE_main.h"
 #include "BKE_report.h"
 #include "BKE_scene.h"
@@ -313,39 +312,28 @@ void WM_main_remove_notifier_reference(const void *reference)
   }
 }
 
-static void wm_main_remap_assetlist(ID *old_id, ID *new_id, void *UNUSED(user_data))
-{
-  ED_assetlist_storage_id_remap(old_id, new_id);
-}
-
-static void wm_main_remap_msgbus_notify(ID *old_id, ID *new_id, void *user_data)
-{
-  struct wmMsgBus *mbus = user_data;
-  if (new_id != NULL) {
-    WM_msg_id_update(mbus, old_id, new_id);
-  }
-  else {
-    WM_msg_id_remove(mbus, old_id);
-  }
-}
-
-void WM_main_remap_editor_id_reference(const struct IDRemapper *mappings)
+void WM_main_remap_editor_id_reference(ID *old_id, ID *new_id)
 {
   Main *bmain = G_MAIN;
 
   LISTBASE_FOREACH (bScreen *, screen, &bmain->screens) {
     LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
       LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
-        ED_spacedata_id_remap(area, sl, mappings);
+        ED_spacedata_id_remap(area, sl, old_id, new_id);
       }
     }
   }
-
-  BKE_id_remapper_iter(mappings, wm_main_remap_assetlist, NULL);
+  ED_assetlist_storage_id_remap(old_id, new_id);
 
   wmWindowManager *wm = bmain->wm.first;
   if (wm && wm->message_bus) {
-    BKE_id_remapper_iter(mappings, wm_main_remap_msgbus_notify, wm->message_bus);
+    struct wmMsgBus *mbus = wm->message_bus;
+    if (new_id != NULL) {
+      WM_msg_id_update(mbus, old_id, new_id);
+    }
+    else {
+      WM_msg_id_remove(mbus, old_id);
+    }
   }
 }
 
diff --git a/source/blender/windowmanager/intern/wm_init_exit.c b/source/blender/windowmanager/intern/wm_init_exit.c
index 6caac79c4d5..957ec7d800d 100644
--- a/source/blender/windowmanager/intern/wm_init_exit.c
+++ b/source/blender/windowmanager/intern/wm_init_exit.c
@@ -252,7 +252,7 @@ void WM_init(bContext *C, int argc, const char **argv)
   BKE_region_callback_free_gizmomap_set(wm_gizmomap_remove);
   BKE_region_callback_refresh_tag_gizmomap_set(WM_gizmomap_tag_refresh);
   BKE_library_callback_remap_editor_id_reference_set(WM_main_remap_editor_id_reference);
-  BKE_spacedata_callback_id_remap_set(ED_spacedata_id_remap_single);
+  BKE_spacedata_callback_id_remap_set(ED_spacedata_id_remap);
   DEG_editors_set_update_cb(ED_render_id_flush_update, ED_render_scene_update);
 
   ED_spacetypes_init();