perf - update window jump list in new phase Eventually (microsoft#159536)

Author: bpasero

src/vs/code/electron-main/app.ts

@@ -109,6 +109,7 @@ import { ExtensionsProfileScannerService, IExtensionsProfileScannerService } fro
 import { IExtensionsScannerService } from 'vs/platform/extensionManagement/common/extensionsScannerService';
 import { ExtensionsScannerService } from 'vs/platform/extensionManagement/node/extensionsScannerService';
 import { UserDataTransientProfilesHandler } from 'vs/platform/userDataProfile/electron-main/userDataTransientProfilesHandler';
+import { RunOnceScheduler, runWhenIdle } from 'vs/base/common/async';
 
 /**
  * The main VS Code application. There will only ever be one instance,
@@ -555,9 +556,16 @@ export class CodeApplication extends Disposable {
 		if (this.environmentMainService.args.trace) {
 			appInstantiationService.invokeFunction(accessor => this.stopTracingEventually(accessor, windows));
 		}
+
+		// Set lifecycle phase to `Eventually` after a short delay and when idle (min 2.5sec, max 5sec)
+		const eventuallyPhaseScheduler = this._register(new RunOnceScheduler(() => {
+			this._register(runWhenIdle(() => this.lifecycleMainService.phase = LifecycleMainPhase.Eventually, 2500));
+		}, 2500));
+		eventuallyPhaseScheduler.schedule();
 	}
 
 	private setUpHandlers(instantiationService: IInstantiationService): void {
+
 		// Auth Handler
 		this._register(instantiationService.createInstance(ProxyAuthHandler));
 

src/vs/platform/lifecycle/electron-main/lifecycleMainService.ts

@@ -175,7 +175,13 @@ export const enum LifecycleMainPhase {
 	 * and is typically the best place to do work that is not required
 	 * for the window to open.
 	 */
-	AfterWindowOpen = 3
+	AfterWindowOpen = 3,
+
+	/**
+	 * The last phase after a window has opened and some time has passed
+	 * (2-5 seconds).
+	 */
+	Eventually = 4
 }
 
 export class LifecycleMainService extends Disposable implements ILifecycleMainService {

src/vs/platform/workspaces/electron-main/workspacesHistoryMainService.ts

@@ -62,8 +62,9 @@ export class WorkspacesHistoryMainService extends Disposable implements IWorkspa
 
 	private registerListeners(): void {
 
-		// Install window jump list after opening window
-		this.lifecycleMainService.when(LifecycleMainPhase.AfterWindowOpen).then(() => this.handleWindowsJumpList());
+		// Install window jump list delayed after opening window
+		// because perf measurements have shown this to be slow
+		this.lifecycleMainService.when(LifecycleMainPhase.Eventually).then(() => this.handleWindowsJumpList());
 
 		// Add to history when entering workspace
 		this._register(this.workspacesManagementMainService.onDidEnterWorkspace(event => this.addRecentlyOpened([{ workspace: event.workspace, remoteAuthority: event.window.remoteAuthority }])));