Your Angular app feels slow mainly because of performance inefficiencies like unnecessary change detection, large bundle sizes, too many API calls, or functions running inside templates. These issues don’t break the app but gradually reduce speed as the application grows.

The most common mistake is using default change detection everywhere. Angular checks all components whenever something changes, which slows down large applications. Using ChangeDetectionStrategy.OnPush helps reduce unnecessary checks and improves performance.

trackBy helps Angular identify list items using a unique ID. Without it, Angular re-renders the entire list even if only one item changes. With trackBy, only updated items are rendered, making UI rendering faster and smoother.

Functions inside templates run on every change detection cycle, even if data hasn’t changed. This repeated execution slows down the UI. Moving logic to the component or using pure pipes prevents unnecessary recalculations and improves performance.

Lazy loading loads only the required modules instead of the entire application at once. This reduces initial load time and improves user experience, especially in large apps with multiple feature modules.