Performance Optimization Techniques in Angular
Performance Optimization Techniques in Angular
The Angular application can be optimized in a variety of ways. Let's begin by examining a couple of techniques in more detail.

Performance Optimization Techniques in Angular

By default, Angular is a quick and efficient framework. However, unexpected problems are bound to come up when creating mission-critical web apps, especially those with complex architectural designs and a lot of information. If you do not know how to create efficient Angular apps, apps will start to become slow as they expand, which will negatively impact the end-user experience. Therefore, any application must be optimized in order to enhance performance and decrease load time.

How to solve this problem?

The Angular application can be optimized in a variety of ways. Let's begin by examining a couple of techniques in more detail.

1. Lazy Loading Module

Only the modules that the user needs at this moment are loaded using a method called lazy loading. This can decrease the initial bundle size and enhance the performance of your application.

2. Using AoT Compilation

There are two methods for compiling your Angular application:

  • During runtime, your app is built using Just-In-Time (JIT) technology
  • Ahead-of-Time (AOT), Compiling the application during the build process

The AoT compilation is available in the Angular 8 afterward version, which improves performance. because the JIT compiles the application while it is running. Additionally, the JIT compilation bundles the compiler with itself, increasing the bundler's size. It also increases the component's rendering time.

As opposed to this, AoT compilation produces only the compiled templates and excludes the compiler, compiling the application during build time. As a result, both rendering time and bundle size significantly decrease. Therefore, we must always use AoT compilation for our applications.

3. Avoid Memory Leaks

A subscription only has the unsubscribe() function to release resources or end observable executions. When we are done with a subscription, we must unsubscribe in order to stop memory leaks. We accomplish this by invoking Observable's unsubscribe method.

In Angular, when a component is being destroyed, we must unsubscribe from the Observable. Fortunately, Angular provides a ngOnDestroy hook that is called before a component is destroyed. This allows developers to dispatch the cleanup crew and prevent dangling subscriptions, open portals, and other potential problems from coming back to bother us in the future.

4. Using Pure Pipes

Pipes are used by Angular to alter data. The use of a pipe improves efficiency. The only function that accepts input and output data that has been transformed is a pipe. Dates, currencies, strings, and other types of information can all be changed using pipes.

The distinction between pure and impure pipes is that a pure pipe generates a comparable output for the same input, whereas an impure pipe can give various outputs for similar types of input. Angular includes several pipes that are all of pure nature.

A pure pipe minimizes value recalculation. When the input differs from the prior value, it returns a value. A pure pipe only detects changes when one of its values changes and the view is updated with the new value provided to the pipe.

5. Using OnPush Change Detection Strategy

The techniques used by the Angular Change Detection Strategy are how updates to the component are tracked and triggered to re-render. In Angular, there are primarily 2 change detection strategies. Inside the Decorator, we may modify the component's change detection strategy.

  • Default Strategy
  • OnPush Strategy

The Child Component is re-rendered as part of the Default Change Detection Strategy each time the counter in the parent component is updated, even if the change in the counter does not affect the child component display. The data of the parent component do not affect the child component. In Detection Strategy for "OnPush". The child component is not always dirty checked during this change detection strategy; if the parent element is modifying values that are not provided to the child component as "@Input" properties, then the child component should not be dirty checked.

6. Use TrackBy

By using TrackBy, you can instruct Angular to associate each DOM element with a value from an item in the array, such as an item's id. If you're rendering an array of items using *ngFor that might change over time. Instead of rendering the full array of DOM elements again the next time the array changes, Angular will simply render and update the updated items.


For any business, performance and load time are crucial. This article demonstrates how optimizing the compilation process can enhance the performance of an application. We observed how change detection, lazy loading, and web workers contributed to our outstanding performance. Understanding the cause of the sluggish performance is necessary before implementing any of the above techniques. Thus, using the proper strategy will enable us to succeed in our endeavors. At Sanesqaure Technologies, we offer the best services for developing Angular applications. If you need any assistance we are here, please chat with us.