enhance: reduce CPU usage

src/Views/LoadingIcon.axaml

@@ -5,5 +5,4 @@
              mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
              xmlns:m="using:SourceGit.Models"
              x:Class="SourceGit.Views.LoadingIcon">
-  <Path x:Name="target" Data="{DynamicResource Icons.Loading}"/>
 </UserControl>

src/Views/LoadingIcon.axaml.cs

@@ -1,6 +1,8 @@
 using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Controls.Shapes;
 using Avalonia.Interactivity;
+using Avalonia.Media;
 
 namespace SourceGit.Views
 {
@@ -15,13 +17,43 @@ namespace SourceGit.Views
         protected override void OnLoaded(RoutedEventArgs e)
         {
             base.OnLoaded(e);
-            target.Classes.Add("rotating");
+            StartAnim();
         }
 
         protected override void OnUnloaded(RoutedEventArgs e)
         {
+            StopAnim();
             base.OnUnloaded(e);
-            target.Classes.Clear();
+        }
+
+        protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property == IsVisibleProperty)
+            {
+                if (IsVisible)
+                    StartAnim();
+                else
+                    StopAnim();                
+            }
+        }
+
+        private void StartAnim()
+        {
+            Content = new Path()
+            {
+                Data = this.FindResource("Icons.Loading") as StreamGeometry,
+                Classes = { "rotating" },
+            };
+        }
+
+        private void StopAnim()
+        {
+            if (Content is Path path)
+                path.Classes.Clear();
+
+            Content = null;
         }
     }
 }