React Native Performance - Optimizing Tips

Introduction

In the age of the Internet, we want everything instantly. A high-performance app can greatly satisfy your customers and can take your business to the next level, while a slow app can kill it.

If you are experienced with mobile apps, you probably hear a lot about React Native performance.

Rightly so.

In this article, you’ll see what kind of app speed you can get with React Native, and how to deal with the performance issues you may face on the way.

React Native performance is… near-native

One of the most interesting benefits of React Native is that it provides near-native performance.

Although React Native isn’t a mobile app native language, it lets you achieve a performance similar to a truly native app, with the benefits of a framework – increased productivity, faster, easier development.

It allows you to optimize your app’s performance by including native code in some areas of your app. That’s how the Facebook app was built.

Although the official site claims that React Native provides native performance, that’s not necessarily true. In order to build native apps that give a native performance, you must use native languages such as Java, Swift, or Objective-C. Java is used for Android development while Swift and Objective-C are used for iOS development.

React Native performance issues and how to solve them

Navigation issues

Although React Native performance is excellent, it still has some issues. For example, the React Native team has been working on addressing problems related to navigation and fixed many of them, but there are still some issues left that need to be fixed.

Just like the overall performance of an app, navigational performance is important as well. If the navigational performance of an app isn’t smooth, it will be hard for the user to access various features of the app. Difficult navigation from one screen to another could prevent users from using your interface.

React Native provides you with, at least, 4 different ways to build a navigation:

• Navigator iOS – can be used only for iOS, won’t help in Android navigation development.
• Navigator – can be used only for small app and prototype development, it isn’t appropriate for complex or high-performance app development.
• Navigation Experiment – has been used in several large apps, but due to the difficulty of use, not everyone likes it (e.g. Airbnb).
• React Navigation – used by a large number of apps and often recommended.

You can also try React Native Navigation. It’s a great navigation tool developed by Wix.

Launch time

Slow app launch is another issue of React Native apps. If your app opens too slowly, you probably have too many dependencies in your app and you’re using slow components. Try to use fast, high-performance components and decrease the number of dependencies in your app.

For example, the Object.Finalize element can increase the app launch time. Use of too many finalizers can result in out-of-memory errors.

Memory leakage

Memory leakage, a React Native performance issue, may occur due to unnecessary processes that run in the background in an Android app. Try using scrolling lists like SectionList, FlatList, or VirtualList, instead of ListView.

Large app size

The size of React Native apps is usually larger than native apps. The app size will increase greatly if you use too many third-party libraries and native components.

To decrease the app size, you may try using fewer third-party libraries and components. You could also compress the images and optimize other resources to reduce the app size.

How do you improve React Native performance?

Use scrolling lists

• For large lists, opt for FlatList or SectionList over the traditional ListView. These components render only the visible items, reducing memory consumption.
• Implement pagination or infinite scrolling to load data in smaller chunks, avoiding the need to load and render all data at once.

Reduce image size

• Utilize image optimization tools like ImageResizer or react-native-fast-image to efficiently load and display images.
• Choose appropriate image formats (JPEG for photos, PNG for graphics) based on image content.
• Use tools like react-native-image-picker to capture or select images in the appropriate resolution.

Reduce application size

• Utilize code splitting and dynamic imports with libraries like react-loadable or the built-in React.lazy for on-demand loading of components.
• Remove unused components, assets, and code paths to reduce the final bundle size.
• Leverage tools like babel-plugin-transform-remove-console to remove console logs from production builds.

Decrease the number of dependencies

• Audit and analyze third-party libraries using tools like npm-check to identify unused or unnecessary dependencies.
• Utilize lightweight alternatives to complex libraries for specific use cases.
• Periodically update dependencies to benefit from bug fixes and performance improvements.

Use only high-performance components

• Benchmark and profile different components using tools like React DevTools or Flipper to identify rendering bottlenecks.
• Replace heavy components with more lightweight alternatives or consider custom implementations when necessary.
• Utilize memoization techniques with React.memo to prevent unnecessary re-renders of components.

Remove unnecessary renders

• Implement shouldComponentUpdate or React.PureComponent to prevent unnecessary re-renders based on prop changes.
• Use the useMemo and useCallback hooks to memoize values and callbacks to prevent unnecessary recalculations.

Try using React Native Navigation tool

• Implement navigation using React Navigation or React Native Navigation libraries based on your project's requirements.
• Utilize native navigation libraries like wix/react-native-navigation for improved performance and smoother transitions.
• Optimize navigation configurations to minimize the rendering of unnecessary screens and components.

Final word

React Native, like every other framework, has certain limitations and issues. Thankfully, there are many effective ways to address them.

Despite a few disadvantages, there are many benefits of using React Native framework, which definitely outweigh its limitations, disadvantages, and issues.