Top 5 Performance Improvements in Angular 18

As Angular continues to evolve, one of the core goals of each release is to boost performance. Angular 18 is no exception, offering significant enhancements to both the development and runtime environments. In this post, we’ll explore the top five performance improvements that make Angular 18 faster and more efficient.

Zoneless Change Detection

Angular 18 introduces the much-anticipated zoneless architecture, allowing developers to drop zones and shift to a more efficient change detection mechanism. Zones have been a core feature since Angular’s early days, enabling automatic tracking of asynchronous operations. However, they add overhead that can slow down large-scale applications.

Key Benefits

• Reduced CPU usage: Zoneless apps no longer require Angular to constantly monitor changes, reducing CPU consumption.
• Finer control over updates: With zoneless mode, developers have more granular control over change detection, updating only specific components when needed, improving overall performance.
• Better support for reactive patterns: Angular now plays more nicely with reactive programming models like RxJS, which naturally fit a zoneless architecture.

  import { ChangeDetectorRef, Component } from '@angular/core';
  
  @Component({
    selector: 'app-example',
    template: `<div>{{ data }}</div>`
  })
  export class ExampleComponent {
    data: string;
  
    constructor(private cd: ChangeDetectorRef) {
      // Trigger change detection only when necessary
      this.cd.detectChanges();
    }
  }

Component-Level Hydration for Server-Side Rendering (SSR)

Server-side rendering (SSR) has been a powerful tool for improving perceived performance and SEO, but Angular 18 has taken it a step further with component-level hydration. This means that when a page is rendered on the server, Angular only re-hydrates the components that need interaction instead of reloading the entire page.

Key Benefits

• Faster initial load: By hydrating individual components rather than the whole app, the page becomes interactive faster.
• Reduced JavaScript payload: This results in less JavaScript being downloaded and executed, leading to quicker load times.
• Improved user experience: Visitors can start interacting with parts of the page while others are still loading in the background.

  import { Component, AfterViewInit } from '@angular/core';
  
  @Component({
    selector: 'app-hydrated-component',
    template: `<div *ngIf="isHydrated">Hydrated Content</div>`
  })
  export class HydratedComponent implements AfterViewInit {
    isHydrated = false;
  
    ngAfterViewInit() {
      // Simulating component hydration
      this.isHydrated = true;
    }
  }

Smaller Bundles with Enhanced Tree Shaking

Angular 18 has improved tree shaking, the process of removing unused code, to help developers deliver smaller bundles. While previous versions of Angular used tree shaking effectively, the new version takes it a step further by incorporating optimizations in module resolution and dependency management.

Key Benefits

• Smaller bundle size: By eliminating unused imports and dead code, Angular 18 generates smaller JavaScript bundles, improving load times and performance.
• Quicker build times: With more efficient tree shaking, the build process is faster, especially for larger applications.

  {
    "compilerOptions": {
      "strict": true,
      "noUnusedLocals": true,
      "noUnusedParameters": true
    }
  }

Make sure to use strict mode in tsconfig.json to maximize tree-shaking capabilities.

ESM Build Support

Angular 18 brings full support for ECMAScript Modules (ESM) builds, which leverage modern browsers’ ability to load JavaScript modules natively. This upgrade allows Angular to better align with the modern web ecosystem and improve performance.

Key Benefits

• Faster loading in modern browsers: By using native module loading, Angular 18 apps load faster in browsers that support ESM.
• Code splitting: ESM support allows more granular control over code splitting, ensuring that only the necessary modules are loaded on demand, improving runtime performance.
• Better cache utilization: Modern browsers can cache individual modules more effectively, reducing load times for repeat visitors.

Optimized Dependency Injection (DI)

Angular 18 improves the Dependency Injection (DI) system by optimizing how services and components are injected into the app. In previous versions, DI could become a performance bottleneck when handling complex dependency graphs. With Angular 18, the DI system has been restructured to minimize overhead.

Key Benefits

• Faster startup times: Optimized DI leads to faster app initialization, especially in large-scale enterprise apps.
• Improved memory efficiency: The new DI system consumes less memory, which is particularly beneficial for applications that have a lot of services or deeply nested components.

Example

The following configuration in the @Injectable decorator helps Angular 18 better manage the injection process.

import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root' // Ensures service is singleton and tree-shakable
})
export class DataService {
  constructor() { }
}

Conclusion

Angular 18 introduces a range of performance improvements that make applications faster, more efficient, and easier to maintain. From zoneless change detection to smaller bundles, each enhancement is designed to give developers greater control and flexibility while delivering better user experiences. If you’re planning to upgrade, these performance enhancements alone make Angular 18 a highly worthwhile transition for modern web apps.

By adopting these new features and best practices, you can ensure your Angular apps remain at the cutting edge of performance and scalability.

Happy Learning!