Best Practices for Developing High-Performance React Native Apps
Maintaining the performance of a React Native app has always been a challenge. In today’s fast-paced world, users are quick to uninstall an app if it doesn’t meet their expectations and switch to a competitor’s offering.
In other words, users have little patience for sluggish or underperforming apps and will readily opt for alternatives.
Developing high-performance React Native apps involves various best practices to ensure a smooth and responsive user experience. Here are some key guidelines to follow:
- Optimize Renders: Use PureComponent or shouldComponentUpdate to prevent unnecessary re-renders. Implement memoization techniques to cache expensive computations. Minimize the use of forceUpdate, as it can lead to inefficient rendering.
- Use Virtualized Lists: Employ FlatList or SectionList for rendering large lists to conserve memory and improve performance. Implement the keyExtractor prop to ensure efficient item updates.
- Image Optimization: Use smaller image dimensions and compression to reduce image size. Employ image-loading libraries like FastImage or react-native-fast-image to enhance loading performance. Lazy load images that are not immediately visible on the screen.
- Bundle Splitting: Split your JavaScript bundle into smaller chunks to reduce the initial load time. Use dynamic imports and code splitting to load modules on demand.
- Avoid Using Redux for Everything: Redux can introduce unnecessary overhead for simple state management. Use it judiciously. Utilize React’s context API for sharing state among components when appropriate.
- Minimize the Use of Third-Party Libraries: Carefully choose third-party libraries to avoid unnecessary bloat. Evaluate libraries for their performance impact and community support.
- Avoid Nesting Styles: Deeply nested styles can lead to slow rendering. Keep your styles as flat as possible. Use StyleSheet.create for defining styles to optimize performance.
- Use the Hermes JavaScript Engine: Hermes is a JavaScript engine optimized for running React Native applications. Consider enabling it for improved startup time and memory efficiency.
- Profile and Optimize: Use profiling tools like React DevTools or Flipper to identify performance bottlenecks. Optimize components, functions, and logic based on profiling results.
- Code Splitting: Split your code into smaller modules and load them only when needed. Use dynamic imports for lazy loading components and libraries.
- Avoid Deep Component Trees: Deep component hierarchies can slow down rendering. Keep your component tree as shallow as possible. Utilize libraries like “reselect” to create memoized selectors for derived data.
- Optimize Network Requests: Minimize unnecessary API requests by caching data and using efficient data fetching strategies. Use pagination and infinite scrolling for long lists to avoid loading all data at once.
- Testing and Profiling: Regularly test and profile your app’s performance on real devices to catch issues early. Keep an eye on memory usage, CPU usage, and frame rates.
- Native Modules and Components: When necessary, implement performance-critical features using native modules and components to leverage the full power of the platform.
- Regularly Update Dependencies: Keep your React Native version and dependencies up to date to benefit from performance improvements and bug fixes.
High-performance React Native apps require a combination of careful design, optimization, and regular monitoring. By following these best practices, you can create apps that provide a responsive and efficient user experience.
1. Fix the Navigation
As mentioned above, navigation issues slow the performance of the app. If the app runs even a millisecond slower, the user will leave and might never return, thus uninstalling the app. Hence, the first issue that needs fixing is Navigation. It can be done in 3 different ways:
- Navigator iOS, which can be used for Apple phones
- Navigator for small apps and prototypes. It cannot be used for more extensive and heavier apps.
- React Navigation is a surefire way to fix the navigation issues.
2. Speed up the Launcher
One can measure an app’s speed by its launcher, which needs proper rendering, reduced memory usage, and shrink the bundle size. These things can be fixed by performance enhancers which are:
- Hermes: Hermes is an open-source and JS-optimized engine that is designed specifically for React Native. This helps reduce the APK download size and restricts memory from getting full. Plus, the best part about it is that it can be used with Android as well as iOS.
- Memoization will prevent rendering: Another way to speed up the launcher and even improve its performance is by memoization. It means speeding up the launch of the app by removing all the caches and elements that are slowing it down. The React Native app developers can either use useMemo or memo to memoize. Both of these help enhance the performance of a React Native app.
3. Avoid using Scroll View.
There are two ways to render the list on the application — one is by integrating ScrollView, and another is by employing FlatList.
According to experts, ScrollView is suggested to be used when the number of elements to be displayed is of limited size and quantity. Hence if your app has features that are tall, heavy, and take up too much space, the use of ScrollView should be avoided.
Instead, using FlatList will render elements that are presented on the screen and not the ones which aren’t. Hence, to avoid exhausting the app and increase its functionality and speed, using FlatList is the best.
4. Optimize Images and React Native Code Beforehand
Before Optimizing Images, you need to cache the image, and for that, you need to understand what problems one can face while caching the images. They are:
- Many images on a single screen
- Slow image loading speed
- Image flickering can be observed
Now, to solve these problems, you need to use the third–party libraries like React Native images that will guide you in improving image health overall. However, it would help if you chose the third-party libraries which can function with both Android and iOS.
Just like one optimizes a blog to rank it in Search Engine Pages, it is standard practice to optimize the code to deliver an application that is not only fast but smooth as well. One of the ways to do so is to employ PureComponent for text. This way, you’ll avoid the risk of overriding the codes. Thus, to avoid doing it later, it is necessary to optimize images and code at the time of developing the app itself.
5. Memory Optimization
Memory leakage could happen due to the heaviness of the app. Hence, it could be solved by using FlatList instead of using ScrollList; you can incorporate SectionList or FlatList.
SectionList supports features like header and footed support, cross-platform, data and item rendering support, etc. FlatList supports everything SectionList supports, and also provides ScrollToIndex support as well as multiple-column support.
Instead of changing it later, do not incorporate ScrollList if the app is going to be more significant. Use it with the prototype. But with the final product, to save the app from memory leakage, try SectionList or FlatList.
6. Fewer Dependencies
Using dependencies in the projects helps the app a lot. However, usage of it could disrupt its performance. It means you are adding unnecessary codes, increasing the size of the bundle.
Even if it saves time in developing the app, it fills the storage when the app becomes more prominent and gets more complex. Eventually, one loses the tract of unused dependencies and forgets to remove them.
Hence, during the creation of the app stage, the developer should take care that not too many dependencies are used.
7. Reduce the App Size
Reducing the app size is the last resort for optimizing the speed. But it is better to be safe than sorry. So instead of reducing the app size at a later stage, it is better to create an app that is already lighter and is not filled with heavy data. This problem occurs mainly while creating apps for Android phones, which makes it difficult for users to download.