Practical Guide to Improving the Performance of React Native Applications

Key Points

• Balance the animation processing of JavaScript (JS) threads and main threads to improve application performance. Use useNativeDriver attributes and InteractionManager to manage this balance.
• Avoid unnecessary component re-rendering. Tips include: memorizing components and functions, using useCallback wisely, avoiding updating local states with Redux states, and avoiding inline functions.
• Optimize images to improve application speed. Use SVG icons and images, WebP image format (lossless image quality), and cache images to speed up rendering.
• Render the project array using stable npm packages and FlatList and avoid memory leaks by logging out the timer/listener/subscribe, avoiding unnecessary use of global variables, and preventing loop object references.
• Drain and monitor performance using analytical tools such as Performance Analytics Tools, Chrome's DevTools, React DevTools, Flipper, and React Native Performance Monitors. Additionally, delete console logs in production mode to enhance application performance.

This article will provide a comprehensive set of tips and strategies to help developers optimize React Native applications to achieve optimal performance and provide an unparalleled user experience.

Animation that balances JS threads and main thread

Anime is a demanding task in any application, and React Native is no exception. React Native uses two main threads: JS threads are used to execute JavaScript code, and the main thread is mainly responsible for rendering the user interface and responding to user input. Animation usually runs on the main thread by default. However, heavy animation workloads on the main thread can cause performance issues such as frame drops.

Solution 1: Try using useNativeDriver

useNativeDriver is a React Native animation property that can be used when animating elements in a React Native application. When the user sets the value of this property to true, the React Native application will render the animation on the main thread. However, if the main thread is expected to be busy with other tasks, you can transfer the animation to the JS thread by setting useNativeDriver: false.

Solution 2: Use InteractionManager

In some cases, both the JS thread and the main thread will be very busy. For example, an application might be fetching API data, executing some logic, and rendering it on the UI. In this case, the JS thread is busy getting data and executing logic, while the main thread is busy showing the UI. Trying to run the animation can cause frame drops and performance issues when both threads are occupied. In this case, InteractionManager can be used. Start the animation first. After the animation is completed, React Native will call InteractionManager.runAfterInteractions to execute the JS code. The JS code will then call the API and display the data on the UI. This method helps to avoid overloading of JS threads executing JS code and animations at the same time.

Avoid unnecessary re-rendering

Avoiding unnecessary re-rendering in React Native is critical to maintaining optimal performance. Whenever the application re-renders, the JS thread creates a JS bundle file and passes it through the React Native bridge, and then hands it to the main thread. The more re-renders the application, the more passes occur between the JS thread and the main thread, which will degrade the performance of the application.

Solution 1: Memory Component

React.memo is a higher-order component provided by React to optimize function components by preventing unnecessary re-rendering. When wrapping a function component with React.memo, React will remember that component, meaning it will re-render the component only if the component's props change. If props between renders remain the same, React will reuse the results of the previous render, thus avoiding the cost of re-rendering the component.

Solution 2: Use the useCallback function wisely

When a parent component sets a callback function for its child component, the callback function is also recreated whenever the parent component re-renders, resulting in a new function reference being returned. Therefore, the child component treats it as a change in the callback function value, causing it to re-render, even if React.memo is used. To mitigate this, you can use useCallback to prevent recreating function references on each re-render of the parent component.

Solution 3: Try to avoid updating local status with Redux status

Solution 4: Memorize the function result

Solution 5: Avoid inline functions

Optimized image

Optimizing images can improve application performance.

Solution 1: Use SVG icons and images

Solution 2: Use WebP Images to get lossless image quality

Solution 3: Cache images to speed up rendering

Use stable NPM package

Use stylesheets to component

Use FlatList to improve performance

Avoid memory leaks

Solution 1: Log out timer/listener/subscribe

Solution 2: Avoid unnecessary use of global variables

Solution 3: Recycling object reference

React Native debugging and performance monitoring tool

1. Performance analysis tool

2. Chrome's DevTools

3. React DevTools

4. Flipper

5. React Native Performance Monitor

Delete console log

Solution 1: Use _DEV_global variable

Use babel-plugin-transform-remove-console

Conclusion

Anyway, optimizing the performance of React Native applications is essential for a seamless user experience. By balancing animations, minimizing rerendering, optimizing images, and using stable npm packages, developers can improve application speed and responsiveness. Additionally, leveraging efficient debugging tools and deleting unnecessary console logs can further improve performance. Prioritizing these optimization techniques ensures optimal performance and excellent user satisfaction in today's competitive application market.

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