The sole reason behind the popularity of the React Native framework is the reusability of code for faster cross-platform app development. But there have been many complaints about performance issues regarding React Native app development. React Native apps often suffer from rendering problems leading to slower loading speed and app performance. Under-optimized coding style leading to expensive rendering can hit the app performance to a great extent.
How to address these performance glitches and shortcomings of React Native apps? Well, considering various aspects here we explained some of the simple methods and measures to boost the speed and performance of React Native apps.
Use PureComponent wherever applicable
While expansive rendering or re-rendering remains a frequent problem leading to performance issues or slower loading speed for React Native apps, React.PureComponent can be utilized to address this issue. React.PureComponent actually brings change to the shouldComponentUpdate life cycle method and allows evaluation of whether re-rendering is required or not.
This actually makes a PureComponent call method render only in case of a necessity such as changes in state or props. This helps brings a change in many components without requiring you to write extra code. This PureComponent also helps in reducing the volume of redundant code for building an app.
Stay Clear of Inline StylesSheet
Inline stylesheet which is widely used and performs quite well can be responsible for reducing the rendering time of various components. This is why it is advisable to stay clear of Inline StyleSheet and instead of that choose Object StyleSheet. The later saves enough time and labor needed for creating a new style object every time.
Object StyleSheet also helps to make a stylesheet from an object that can be referred with a specific ID for future use. Every subsequent use can just refer to the assigned ID of the style. This brings down the complexity of the development process and also adds to the simplicity of the app.
Not declaring function inside rendering method
When you declare a function inside the rendering method, it is required to be redeclared each and every time rendering method is called upon. This ultimately leads to the shortcomings in the app view and app performance.
Such cases where function inside the rendering method leads to multiple re-rendering and consequent slower app performance and speed are too many among the React Native apps. This is why declaring function inside the rendering method needs to be avoided for superior app output.
Make use of key attribute on the list items
The list is found as a common attribute across too many applications. Often these List items in a React Native app are re-rendered again and again that causes considerable app performance issues. If the List items within an app are not provided separate keys, they will be re-rendered every time any item is removed from the list or added to the list. To save the app from this re-rendering of the List items, using unique keys for every List item is very important.
Allow asynchronous rendering of expensive tasks
Since React Native is a JavaScript-based framework with the views and functions written in JavaScript, asynchronous calling of API calls is very necessary so that other activities are carried out smoothly. This is why maintaining the asynchronous character of expensive tasks is so crucial for the React Native app.
Boost the performance of static image
To understand the speed and performance issues of React Native apps it is important to understand how loading assets like images cause slower app performance. In the instances of loading assets right from the JavaScript package, the asset file is picked up from the package, and then it is delivered to the UI layer over the bridge.
Now, this process can be given a speed-boost by optimizing the static image files. The developers can use Xcode asset catalogs to detect assets that are already within the asset package. This will just help React just tell the UI layer to render any specific image.
Thanks to the Xcode, this is particularly easier for the iOS platform. In the case of Android, the process is a bit complex.
Maintain A Global State
Managing states in an app involves some crucial performance issues that can be easily solved with the time-tested practices. For a React Native app minimising the calls to setState is important for faster performance. To achieve this, it is advisable to use Redux libraries for taking care of the states in the app. Besides this, Redux library also helps in syncing the app state with the views.
For large data sets make use of VirtualizedList, FlatList and SectionList
According to the React Native docs, to boost the performance of app UIs, use of
VirtualizedList, FlatList and SectionList can play a very important role. To make lists appear in a more user-friendly manner VirtualizedList can be utilized. Though both
FlatList and SectionList depend upon VirtualizedList, one can always use VirtualizedList directly in case of immutable data sets.
Utilize Perf monitor for seeing FPS
Among the React Native developer tools, you will have the Perf monitor to keep track of FPS speed. After beginning to interact, navigate, and scroll through an app, a drop in FPS is often experienced by the users. This happens particularly on the JS thread instead of on the native UI thread. This is why for detecting the pain points it is important to track where FPS is dropping.
Upon inspection you may come to know about the reasons behind the problem and solve the issues. You might have put setting state or dispatched redux actions at the wrong places. Or else, this might have been caused due to too much synchronous work on the JS thread. By using the Perf monitor you can detect the FPS speed dropping and accordingly can address the causes.
Conclusion
The above-mentioned ways and measures have already been proved to be highly effective for boosting the performance and speed of React Native mobile apps. React Native is already regarded as a performance-focused framework which gets a further speed boost through these measures.
