From 88d949568e04f7cf36ca5724c7976352ef98a5fa Mon Sep 17 00:00:00 2001
From: Stefan Dirix <sdirix@eclipsesource.com>
Date: Tue, 12 Sep 2023 16:27:52 +0200
Subject: [PATCH] chore: improve frontend startup performance

The frontend awaits 'initialize', 'configure' and 'onStart' for all
frontend contributions. It's therefore very important that no expensive
code is run there.

By not awaiting expensive operations in

 - DebugFrontendApplicationContribution.onStart (~300ms)
 - EditorNavigationContribution.onStart (~36-400ms)
 - TerminalFrontendContribution.onStart (~100-300ms)

the reported startup time without using plugins is reduced by ~400-1000ms
which is an improvement of ~20-40%.

Contributed on behalf of STMicroelectronics
---
 CHANGELOG.md                                                  | 1 +
 packages/core/src/browser/common-frontend-contribution.ts     | 1 +
 .../src/browser/debug-frontend-application-contribution.ts    | 4 ++--
 packages/editor/src/browser/editor-navigation-contribution.ts | 2 +-
 .../terminal/src/browser/terminal-frontend-contribution.ts    | 2 +-
 5 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6d7ec86fcf408..c6877416ae1cb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 ## v1.42.0
 
 - [core] fixed logger level propagation when log config file changes at runtime [#12566](https://github.com/eclipse-theia/theia/pull/12566) - Contributed on behalf of STMicroelectronics
+- [core] improve frontend startup time [#12936](https://github.com/eclipse-theia/theia/pull/12936) - Contributed by STMicroelectronics
 - [vsx-registry] added a hint to extension fetching ENOTFOUND errors [#12858](https://github.com/eclipse-theia/theia/pull/12858) - Contributed by STMicroelectronics
 
 ## v1.41.0 - 08/31/2023
diff --git a/packages/core/src/browser/common-frontend-contribution.ts b/packages/core/src/browser/common-frontend-contribution.ts
index 7df314fd08cb5..c446f1e88c729 100644
--- a/packages/core/src/browser/common-frontend-contribution.ts
+++ b/packages/core/src/browser/common-frontend-contribution.ts
@@ -428,6 +428,7 @@ export class CommonFrontendContribution implements FrontendApplicationContributi
     protected pinnedKey: ContextKey<boolean>;
 
     async configure(app: FrontendApplication): Promise<void> {
+        // FIXME: This request blocks valuable startup time (~200ms).
         const configDirUri = await this.environments.getConfigDirUri();
         // Global settings
         this.encodingRegistry.registerOverride({
diff --git a/packages/debug/src/browser/debug-frontend-application-contribution.ts b/packages/debug/src/browser/debug-frontend-application-contribution.ts
index 4ca406c3860b4..5e833a8a39f29 100644
--- a/packages/debug/src/browser/debug-frontend-application-contribution.ts
+++ b/packages/debug/src/browser/debug-frontend-application-contribution.ts
@@ -473,8 +473,8 @@ export class DebugFrontendApplicationContribution extends AbstractViewContributi
 
         this.schemaUpdater.update();
         this.configurations.load();
-        await this.breakpointManager.load();
-        await this.watchManager.load();
+        this.breakpointManager.load();
+        this.watchManager.load();
     }
 
     onStop(): void {
diff --git a/packages/editor/src/browser/editor-navigation-contribution.ts b/packages/editor/src/browser/editor-navigation-contribution.ts
index 9aa98da47d800..36c5ed2ad6d50 100644
--- a/packages/editor/src/browser/editor-navigation-contribution.ts
+++ b/packages/editor/src/browser/editor-navigation-contribution.ts
@@ -175,7 +175,7 @@ export class EditorNavigationContribution implements Disposable, FrontendApplica
     }
 
     async onStart(): Promise<void> {
-        await this.restoreState();
+        this.restoreState();
     }
 
     onStop(): void {
diff --git a/packages/terminal/src/browser/terminal-frontend-contribution.ts b/packages/terminal/src/browser/terminal-frontend-contribution.ts
index a4feb00b0c0a6..5ca103b796db7 100644
--- a/packages/terminal/src/browser/terminal-frontend-contribution.ts
+++ b/packages/terminal/src/browser/terminal-frontend-contribution.ts
@@ -268,7 +268,7 @@ export class TerminalFrontendContribution implements FrontendApplicationContribu
     }
 
     async onStart(app: FrontendApplication): Promise<void> {
-        await this.contributeDefaultProfiles();
+        this.contributeDefaultProfiles();
 
         this.terminalPreferences.onPreferenceChanged(e => {
             if (e.preferenceName.startsWith('terminal.integrated.')) {