diff --git a/Flow.Launcher/ViewModel/MainViewModel.cs b/Flow.Launcher/ViewModel/MainViewModel.cs
index 0a1ef8d81..f71674774 100644
--- a/Flow.Launcher/ViewModel/MainViewModel.cs
+++ b/Flow.Launcher/ViewModel/MainViewModel.cs
@@ -469,9 +469,9 @@ namespace Flow.Launcher.ViewModel
             }
             else
             {
+                _updateSource?.Cancel();
                 Results.Clear();
                 Results.Visbility = Visibility.Collapsed;
-                
             }
         }
 
@@ -695,7 +695,9 @@ namespace Flow.Launcher.ViewModel
                 _saved = true;
             }
         }
-
+        /// <summary>
+        /// To avoid deadlock, this method should not called from main thread
+        /// </summary>
         public void UpdateResultView(IEnumerable<ResultsForUpdate> resultsForUpdates)
         {
             foreach (var result in resultsForUpdates.SelectMany(u => u.Results))
diff --git a/Flow.Launcher/ViewModel/ResultsViewModel.cs b/Flow.Launcher/ViewModel/ResultsViewModel.cs
index d06a390c5..635b20ec6 100644
--- a/Flow.Launcher/ViewModel/ResultsViewModel.cs
+++ b/Flow.Launcher/ViewModel/ResultsViewModel.cs
@@ -174,7 +174,6 @@ namespace Flow.Launcher.ViewModel
                     Margin = new Thickness { Top = 0 };
                     Visbility = Visibility.Collapsed;
                     break;
-
             }
         }
 
@@ -247,7 +246,7 @@ namespace Flow.Launcher.ViewModel
 
         public class ResultCollection : ObservableCollection<ResultViewModel>, INotifyCollectionChanged
         {
-            public event NotifyCollectionChangedEventHandler CollectionChanged;
+            public override event NotifyCollectionChangedEventHandler CollectionChanged;
             public void RemoveAll()
             {
                 ClearItems();
@@ -259,12 +258,16 @@ namespace Flow.Launcher.ViewModel
             /// <param name="newItems"></param>
             public void Update(List<ResultViewModel> newItems)
             {
+
+
                 ClearItems();
 
                 foreach (var item in newItems)
                 {
                     Add(item);
                 }
+
+                // wpf use directx / double buffered already, so just reset all won't cause ui flickering
                 CollectionChanged?.Invoke(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
 
                 return;