All about React Native performance
Published at June 28, 2018

React Native is one of the most popular mobile app development tools. It’s free and open-source. It has been developed by Facebook and was released in March, 2015.

It’s a cross-platform framework. You can use it to develop Android and iOS apps.

React Native is available on GitHub. It’s a very popular framework which has 64,995 stars and 1,676 contributors on GitHub, as of writing this article.

One of the main benefits of using a framework is that you can complete a project faster. The same is true for React Native. It lets you develop a mobile app quickly. But a disadvantage of using a framework is that you will not get truly native performance.

In this article, I will discuss React Native performance in short. I hope you will find it useful.

So let’s start!

Near-native performance

The official site of React Native may claim that you can build a native mobile app using React Native or that you can achieve native performance using this framework. But I have understood that a framework cannot give you a truly native performance. This is why I say React Native gives your app near-native performance.

With React Native, you get awesome performance. It allows you to use native code (such as Java, Swift, and Objective-C code) in your app. You can build some feature of your app in native code for a better performance and the rest of the app’s features in React Native. This is how the Facebook is built.

React Native gives amazing performance to your mobile app. But you should know that there are performance issues, too. In the next sections of this article, I will talk about React Native performance issues and will also talk about how to fix them.

Large app size

One of the issues of a React Native app is that the app size is generally larger than the native apps. Native components and third-party libraries are used while building a React Native app. So the app size increases.

There are many ways you can decrease the app size. For example, you can use fewer components and libraries in your app. You can also optimize the resources and compress images to reduce the app size.

Memory leakage

Memory leakage is another performance issue in a React Native app. In Android apps, memory leaks occur because of unnecessary processes running in the background. If you want to fix memory leaks in an Android app, use scrolling lists. Do not use ListView. Instead, use other scrolling lists such as SectionList, VirtualList, or FlatList.

Navigation issues

There are navigation issues in a React Native app. The navigation performance is not so good, although the development team of React Native is trying to improve the navigation performance. Improving the navigation performance is very important because if there are navigation problems, the app will not be that user-friendly, which means it will be a little harder to use the app.

There are 4 navigation components in React Native. They are: Navigator, Navigator iOS, Navigation Experiment, and ReactNavigation. The Navigator component will not be a good fit if you want to develop high-performance apps. It’s mainly used for prototyping and in building small apps. The Navigator iOS component is as same as the Navigator component, which is used in iOS apps.

The Navigation Experiment component is used by a good number of apps but Airbnb did not find it easy to use.

The ReactNavigation component is an awesome component, used by 60% of React Native apps. You will get smooth performance with this component.

Launch time

If it takes too much time to launch an app, the user will get annoyed and will probably uninstall the app. It becomes frustrating especially when the user needs to use the app several times a day. So if the app launches instantly, the app users will be happy to use the app.

So improving the app launch time is very important.

To improve the app launch time, you first need to know why your app takes so long to launch. The components that you’re using may be slowing your app. So you have to search for better performing components and use them. You also have to reduce dependencies.

The Object.Finalize element can slow down your app. Even if you do not use many finalizers, they can cause out-of-memory errors. As finalizers are executed on a single thread, it would take so much time for them to be executed if there are too many finalizers. All of the finalizers cannot run concurrently, they have to wait. This kind of dependencies on your app increases the launch time.

Final words

In this post, I have talked about React Native performance. I have explained a few React Native performance issues in this article and have explained how to fix them. There are many other issues.

For example, your React Native app may crash when the app user changes the screen orientation. Multiple threading is not supported by this framework. So multiple services cannot execute at the same time. You may face difficulties while implementing infinite scrolling.

These problems are not unknown to the developers’ community. Developers from all over the world have spotted these issues and have also come with solutions. You will find many articles on the Internet explaining how to solve these problems.

Although there are performance issues in React Native, it is undoubtedly an awesome mobile app development framework. Every framework has its advantages and disadvantages. The reason why React Native is in huge demand is that its overall quality is good enough although there are drawbacks. In other words, in case of React Native, the advantages outweigh the disadvantages.

Do you need to develop mobile apps? We have experts at Virtual Spirit who can build high-performance mobile apps for you using React Native and Ionic. If you want to hire us, call us at +60197570530 or email us at hello@virtualspirit.me.

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