From 4d7224555268fbcddaf0a46e18497ec84ef5f5cb Mon Sep 17 00:00:00 2001
From: Juha <juha@lazarus-ide.org>
Date: Thu, 27 Jan 2022 13:21:16 +0200
Subject: [PATCH] LCL: Solve most performance issues with virtual TListView
 (OwnerData=True). Issue #39324, patch by d7_2_laz.

---
 lcl/include/customlistview.inc | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/lcl/include/customlistview.inc b/lcl/include/customlistview.inc
index affd0a2b8c..c0e8cd0908 100644
--- a/lcl/include/customlistview.inc
+++ b/lcl/include/customlistview.inc
@@ -1443,13 +1443,19 @@ begin
     if not (lffSelectedValid in FFlags) or MultiSelect then
     begin
       FSelected := nil;
-      for i := 0 to Items.Count - 1 do
+      if (not FOwnerData) or (FSelectedIdx >= 0) then
       begin
-        if Items[i].Selected then
-        begin
-          FSelected := Items[i];
-          break;
-        end;
+        if MultiSelect and FOwnerData and (FSelectedIdx >= 0) then
+          FSelected := Items[FSelectedIdx]
+        else
+          for i := 0 to Items.Count - 1 do
+          begin
+            if Items[i].Selected then
+            begin
+              FSelected := Items[i];
+              break;
+            end;
+          end;
       end;
       Include(FFlags, lffSelectedValid);
     end;