---
title: "What are some ways to improve the performance of an AngularJS application?"  
description: "What are some ways to improve the performance of an AngularJS application?"  
author: "ICSM Computer"  
published: 2025-03-30  
updated: 2025-03-30  
canonical: https://www.mindstick.com/interview/34018/what-are-some-ways-to-improve-the-performance-of-an-angularjs-application  
category: "angular js"  
tags: ["javascript", "angular js"]  
reading_time: 4 minutes  

---

# What are some ways to improve the performance of an AngularJS application?

Improving the performance of an AngularJS application involves optimizing various aspects such as data binding, digest cycle efficiency, lazy loading, and reducing unnecessary computations. Here are some key strategies:

#### 1. Optimize Digest Cycle

1. Use `ng-if` instead of `ng-show/ng-hide`

   1. ng-if removes the element from the DOM, while ng-show just hides it, reducing the number of watchers.

2. Minimize `ng-repeat` usage

   1. Use one-time binding `(::)` for static data.
   2. Use track by to improve performance:\ `<div ng-repeat="item in items track by item.id">`

3. Consider pagination or infinite scrolling to reduce large lists.

#### 2. Reduce Watchers & Bindings

1. Use `one-time binding (::)` for data that doesn’t change:
2. Remove unnecessary `$watch` expressions.\ `<h1>{{ ::title }}</h1>`
3. Use `debouncing` or throttling for events like `keyup` or scroll using `lodash` or `$timeout`.

#### 3. Lazy Loading & Minification

1. **Lazy load Angular modules** using `ocLazyLoad` or `ui-router’s` `resolve`.
2. **Minify and concatenate** JavaScript and CSS files to reduce HTTP requests.

####

#### 4. Optimize Filters & Expressions

1. Avoid using filters inside `ng-repeat` as they create a new function call in each digest cycle:\ `<div ng-repeat="user in users | filter:searchText">`\ Instead, use pre-filtering in the controller:\ `$scope.filteredUsers = $filter('filter')($scope.users, $scope.searchText);`
2. Use **limitTo** instead of `filter` inside `ng-repeat` where possible.

#### 5. Optimize API Calls

1. Use **$cacheFactory** or **localStorage** to store API responses.
2. Debounce API calls when typing in a search input.
3. Use **resolve** in `ui-router` to fetch data before rendering a view.

#### 6. Use `bindOnce` for Directives

1. In custom directives, avoid `scope: {}` for static data.
2. Use `bindToController: true` for better performance.

#### 7. Avoid Deep Watches

1. `$scope.$watch` with deep watching (`true` as the third argument) slows down performance. Avoid it if possible:

```javascript
$scope.$watch('largeObject', function(newVal, oldVal) {
    // Avoid deep watch if not necessary
}, true);
```

#### 8. Optimize DOM Manipulations

Use **directives instead of controllers** to manipulate the DOM.

Use `$timeout` or `$applyAsync` to batch updates and reduce digest cycles.

#### 9. Reduce Dependencies

Remove unnecessary third-party libraries.

Use AngularJS' built-in services instead of external ones if possible.

#### 10. Enable Production Mode

Use `ng-strict-di` to catch dependency injection issues in production.

Minify and use AngularJS in production mode (`angular.min.js`).

## Answers

### Answer by ICSM Computer

Improving the performance of an AngularJS application involves optimizing various aspects such as data binding, digest cycle efficiency, lazy loading, and reducing unnecessary computations. Here are some key strategies:

#### 1. Optimize Digest Cycle

1. Use `ng-if` instead of `ng-show/ng-hide`

   1. ng-if removes the element from the DOM, while ng-show just hides it, reducing the number of watchers.

2. Minimize `ng-repeat` usage

   1. Use one-time binding `(::)` for static data.
   2. Use track by to improve performance:\ `<div ng-repeat="item in items track by item.id">`

3. Consider pagination or infinite scrolling to reduce large lists.

#### 2. Reduce Watchers & Bindings

1. Use `one-time binding (::)` for data that doesn’t change:
2. Remove unnecessary `$watch` expressions.\ `<h1>{{ ::title }}</h1>`
3. Use `debouncing` or throttling for events like `keyup` or scroll using `lodash` or `$timeout`.

#### 3. Lazy Loading & Minification

1. **Lazy load Angular modules** using `ocLazyLoad` or `ui-router’s` `resolve`.
2. **Minify and concatenate** JavaScript and CSS files to reduce HTTP requests.

####

#### 4. Optimize Filters & Expressions

1. Avoid using filters inside `ng-repeat` as they create a new function call in each digest cycle:\ `<div ng-repeat="user in users | filter:searchText">`\ Instead, use pre-filtering in the controller:\ `$scope.filteredUsers = $filter('filter')($scope.users, $scope.searchText);`
2. Use **limitTo** instead of `filter` inside `ng-repeat` where possible.

#### 5. Optimize API Calls

1. Use **$cacheFactory** or **localStorage** to store API responses.
2. Debounce API calls when typing in a search input.
3. Use **resolve** in `ui-router` to fetch data before rendering a view.

#### 6. Use `bindOnce` for Directives

1. In custom directives, avoid `scope: {}` for static data.
2. Use `bindToController: true` for better performance.

#### 7. Avoid Deep Watches

1. `$scope.$watch` with deep watching (`true` as the third argument) slows down performance. Avoid it if possible:

```javascript
$scope.$watch('largeObject', function(newVal, oldVal) {
    // Avoid deep watch if not necessary
}, true);
```

#### 8. Optimize DOM Manipulations

Use **directives instead of controllers** to manipulate the DOM.

Use `$timeout` or `$applyAsync` to batch updates and reduce digest cycles.

#### 9. Reduce Dependencies

Remove unnecessary third-party libraries.

Use AngularJS' built-in services instead of external ones if possible.

#### 10. Enable Production Mode

Use `ng-strict-di` to catch dependency injection issues in production.

Minify and use AngularJS in production mode (`angular.min.js`).


---

Original Source: https://www.mindstick.com/interview/34018/what-are-some-ways-to-improve-the-performance-of-an-angularjs-application

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