[WinForms] Fix ListView GetItemAt high load (#19639)

When ListView.VirtualMode = true GetItemAt should not access items collection directly to
get bounds of ListViewItem. Otherwise, method OnRetrieveVirtualItem will be called.
Which costs a lot of time.

1 files changed, 1 insertions, 1 deletions

diff --git a/mcs/class/System.Windows.Forms/System.Windows.Forms/ListView.cs b/mcs/class/System.Windows.Forms/System.Windows.Forms/ListView.cs
index a8854afd6ef..13cda57f3ab 100644
--- a/mcs/class/System.Windows.Forms/System.Windows.Forms/ListView.cs
+++ b/mcs/class/System.Windows.Forms/System.Windows.Forms/ListView.cs
@@ -3852,7 +3852,7 @@ namespace System.Windows.Forms
 		{
 			Size item_size = ItemSize;
 			for (int i = 0; i < items.Count; i++) {
-				Rectangle item_rect = items [i].Bounds;
+				Rectangle item_rect = new Rectangle(GetItemLocation(i), item_size);
 				if (item_rect.Contains (x, y))
 					return items [i];
 			}