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How do you optimize an Angular app for performance?

Optimizing an Angular app for performance involves both build-time and run-time strategies. Here's a comprehensive breakdown:

How do you optimize an Angular app for performance?

๐Ÿš€ Top Angular Performance Optimization Techniques

๐Ÿ”ง 1. Use Ahead-of-Time (AOT) Compilation

  • Compiles your code before the browser loads it.

  • Reduces bundle size and improves startup time.

ng build --prod

(AOT is enabled by default in production mode.)

๐Ÿ“ฆ 2. Enable Production Mode

  • Disables development-specific checks and change detection warnings.

import { enableProdMode } from '@angular/core'; if (environment.production) { enableProdMode(); }

๐ŸŒณ 3. Tree Shaking & Lazy Loading

  • Tree shaking removes unused code during build.

  • Lazy loading defers loading feature modules until they're needed.

const routes: Routes = [ { path: 'admin', loadChildren: () => import('./admin/admin.module').then(m => m.AdminModule) } ];

๐Ÿข 4. Avoid Unnecessary Change Detection

  • Use ChangeDetectionStrategy.OnPush for components where inputs are immutable.

@Component({ changeDetection: ChangeDetectionStrategy.OnPush })

๐Ÿงผ 5. Optimize Template Expressions

  • Keep expressions in templates simple and fast.

  • Avoid calling functions in templates (they get called on every change detection).

<!-- Avoid this --> {{ computeValue() }} <!-- Better --> {{ cachedValue }}

๐Ÿ“ 6. TrackBy in ngFor

  • Prevents Angular from re-rendering entire lists unnecessarily.


<li *ngFor="let item of items; trackBy: trackById"></li>

trackById(index: number, item: any) { return item.id; }

๐Ÿ’พ 7. Preload Critical Resources & Use Lazy Loading Wisely


RouterModule.forRoot(routes, { preloadingStrategy: PreloadAllModules })

๐Ÿงฑ 8. Minimize Bundle Size

npm install -g source-map-explorer source-map-explorer dist/main.js
  • Remove unused imports, third-party packages, and polyfills.

๐Ÿ“‰ 9. Optimize Images & Assets

  • Use optimized image formats (webp, avif)

  • Lazy-load large images and components

๐Ÿงช 10. Use Service Workers (PWA)

  • Enable caching with Angular Service Workers to serve files faster.


ng add @angular/pwa

✅ Bonus Tips

  • Avoid memory leaks by unsubscribing from observables.

  • Use trackBy, async pipe, and debounceTime in forms and search inputs.

  • Avoid frequent console.log() in production.

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