Code Quality: Faster background launch at Windows startup (#14464)

Author: hishitetsu

src/Files.App/App.xaml.cs

@@ -135,17 +135,25 @@ async Task ActivateAsync()
 
 					_ = MainWindow.Instance.InitializeApplicationAsync(appActivationArguments.Data);
 				}
-
-				await AppLifecycleHelper.InitializeAppComponentsAsync();
-
-				if (isStartupTask && isLeaveAppRunning)
+				else
 				{
-					// Create a system tray icon when initialization is done
+					// Create a system tray icon
 					SystemTrayIcon = new SystemTrayIcon().Show();
-					App.Current.Exit();
+
+					// Sleep current instance
+					Program.Pool = new(0, 1, $"Files-{ApplicationService.AppEnvironment}-Instance");
+
+					Thread.Yield();
+
+					if (Program.Pool.WaitOne())
+					{
+						// Resume the instance
+						Program.Pool.Dispose();
+						Program.Pool = null;
+					}
 				}
-				else
-					await AppLifecycleHelper.CheckAppUpdate();
+
+				await AppLifecycleHelper.InitializeAppComponentsAsync();
 			}
 		}
 

src/Files.App/Helpers/Application/AppLifecycleHelper.cs

@@ -52,6 +52,8 @@ await Task.WhenAll(
 
 			FileTagsHelper.UpdateTagsDb();
 
+			await CheckAppUpdate();
+
 			static Task OptionalTaskAsync(Task task, bool condition)
 			{
 				if (condition)