Angular Performance

Angular Performance

Version: Angular 21 (2025) Tags: Performance, Optimization, Bundle Size, Change Detection

References: Performance Guide • Change Detection

API Changes

This section documents recent version-specific API changes.

• NEW: Zoneless change detection — Disable zone.js for better performance source

• NEW: Deferrable views (@defer) — Lazy load component code

• NEW: Signal-based reactivity — Use signals instead of zone.js

• NEW: afterNextRender — Run code after rendering without zone.js

Best Practices

• Use OnPush change detection strategy

@Component({
  changeDetection: ChangeDetectionStrategy.OnPush,
  // ...
})
export class MyComponent {}

• Use trackBy with @for

@Component({
  template: `
    @for (item of items; track item.id) {
      {{ item.name }}
    }
  `
})
export class MyComponent {}

• Use lazy loading for routes