diff --git a/src/App.xaml.cs b/src/App.xaml.cs
index dadd88be..f4b5e643 100644
--- a/src/App.xaml.cs
+++ b/src/App.xaml.cs
@@ -120,6 +120,7 @@ namespace SourceGit {
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void OnAppDeactivated(object sender, EventArgs e) {
+            GC.Collect();
             if (!restart) Models.Preference.Save();
         }
     }
diff --git a/src/Views/Controls/Avatar.cs b/src/Views/Controls/Avatar.cs
index eebd2264..5dfe9eb7 100644
--- a/src/Views/Controls/Avatar.cs
+++ b/src/Views/Controls/Avatar.cs
@@ -80,6 +80,21 @@ namespace SourceGit.Views.Controls {
 
         public Avatar() {
             SetValue(RenderOptions.BitmapScalingModeProperty, BitmapScalingMode.HighQuality);
+            Unloaded += (o, e) => Cancel(Email);
+        }
+
+        /// <summary>
+        ///     取消一个下载任务
+        /// </summary>
+        /// <param name="email"></param>
+        private void Cancel(string email) {
+            if (!string.IsNullOrEmpty(email) && requesting.ContainsKey(email)) {
+                if (requesting[email].Count <= 1) {
+                    requesting.Remove(email);
+                } else {
+                    requesting[email].Remove(this);
+                }
+            }
         }
 
         /// <summary>
@@ -139,15 +154,7 @@ namespace SourceGit.Views.Controls {
             Avatar a = d as Avatar;
             if (a == null) return;
 
-            var oldEmail = e.OldValue as string;
-            if (!string.IsNullOrEmpty(oldEmail) && requesting.ContainsKey(oldEmail)) {
-                if (requesting[oldEmail].Count <= 1) {
-                    requesting.Remove(oldEmail);
-                } else {
-                    requesting[oldEmail].Remove(a);
-                }
-            }
-
+            a.Cancel(e.OldValue as string);
             a.Source = null;
             a.InvalidateVisual();
 
@@ -181,6 +188,8 @@ namespace SourceGit.Views.Controls {
             requesting[email].Add(a);
 
             Action job = () => {
+                if (!requesting.ContainsKey(email)) return;
+
                 try {
                     HttpWebRequest req = WebRequest.CreateHttp(Models.Preference.Instance.General.AvatarServer + md5 + "?d=404");
                     req.Timeout = 2000;
diff --git a/src/Views/Launcher.xaml.cs b/src/Views/Launcher.xaml.cs
index d5ca5344..2f2d3964 100644
--- a/src/Views/Launcher.xaml.cs
+++ b/src/Views/Launcher.xaml.cs
@@ -87,10 +87,11 @@ namespace SourceGit.Views {
         }
 
         private void OnTabClosed(object sender, Widgets.PageTabBar.TabEventArgs e) {
+            Controls.PopupWidget.UnregisterContainer(e.TabId);
             Models.Watcher.Close(e.TabId);
             Commands.AutoFetch.Stop(e.TabId);
             container.Remove(e.TabId);
-            Controls.PopupWidget.UnregisterContainer(e.TabId);
+            GC.Collect();
         }
         #endregion
     }
diff --git a/src/Views/Widgets/Dashboard.xaml.cs b/src/Views/Widgets/Dashboard.xaml.cs
index bae2ecee..0ed1c376 100644
--- a/src/Views/Widgets/Dashboard.xaml.cs
+++ b/src/Views/Widgets/Dashboard.xaml.cs
@@ -68,6 +68,15 @@ namespace SourceGit.Views.Widgets {
             watcher.StashChanged += UpdateStashes;
             watcher.TagChanged += UpdateTags;
             watcher.SubmoduleChanged += UpdateSubmodules;
+
+            Unloaded += (o, e) => {
+                localBranches.Clear();
+                remoteBranches.Clear();
+                localBranchTree.ItemsSource = localBranches;
+                remoteBranchTree.ItemsSource = remoteBranches;
+                tagList.ItemsSource = new List<Models.Tag>();
+                submoduleList.ItemsSource = new List<string>();
+            };
         }
 
         #region POPUP
diff --git a/src/Views/Widgets/Histories.xaml.cs b/src/Views/Widgets/Histories.xaml.cs
index 73f6a126..be900ac1 100644
--- a/src/Views/Widgets/Histories.xaml.cs
+++ b/src/Views/Widgets/Histories.xaml.cs
@@ -27,6 +27,12 @@ namespace SourceGit.Views.Widgets {
             var watcher = Models.Watcher.Get(repo.Path);
             watcher.BranchChanged += UpdateCommits;
             watcher.TagChanged += UpdateCommits;
+
+            Unloaded += (o, e) => {
+                cachedCommits.Clear();
+                commitList.ItemsSource = cachedCommits;
+                graph.SetData(cachedCommits, false);
+            };
         }
 
         #region DATA
diff --git a/src/Views/Widgets/RevisionFiles.xaml.cs b/src/Views/Widgets/RevisionFiles.xaml.cs
index 4e6fcb55..904ac54b 100644
--- a/src/Views/Widgets/RevisionFiles.xaml.cs
+++ b/src/Views/Widgets/RevisionFiles.xaml.cs
@@ -31,6 +31,7 @@ namespace SourceGit.Views.Widgets {
 
         public RevisionFiles() {
             InitializeComponent();
+            Unloaded += (o, e) => treeFiles.ItemsSource = new List<FileNode>();
         }
 
         public void SetData(string repo, string sha, Commands.Context cancelToken) {