React Native Performance Optimization: A Detailed Guide to Optimize React Native App

React Native Performance Optimization

React Native Performance Optimization: A Comprehensive Guide to Improving the Speed and Efficiency of Your React Native App

With the rise of mobile apps, performance is a growing concern, and with good reason. Performance optimization is an art form and requires practical knowledge of programming languages and frameworks in general. Many developers have built a career out of optimizing computer systems but do you know how to improve your app’s performance?

It’s a great choice for many developers because it’s easy to learn, it has a large community, and it can be used for cross-platform development. However, React Native is not without its performance issues. In this article, we’ll discuss some of the major performance issues in React Native and provide insights on how to improve your react native performance optimization app’s performance.

One of the significant issues with React Native is its use of JavaScript. JavaScript is a dynamic language that doesn’t have the same level of optimization as languages like C++. This means that your app will likely have some performance issues if you use React Native. Another issue with React Native is its use of the bridge. The bridge is what allows communication between the native code and the JavaScript code. This can lead to performance issues because the bridge has to be constantly updated.

There are some ways to improve the performance of your app if you’re using React Native. One way is to use a static type checker like Flow or TypeScript. This will help catch errors early and prevent them from happening in production. You can also use a tool like Hermes.

React Native Slowlog Improves performance issues in React Native

If you want to learn the REAL cause of performance limitations in React Native apps, read on. React Native Slowlog does wonders when it comes to speed issues with your app. You’ll get to add a custom threshold and create a baseline for your future improvements. All you need to do is add this one line of code inside your view’s constructor and you’re good to go!

React Native has some Issues with Performance on Android Devices

Memory Leak in Android

There are a couple of factors that can cause a memory leak in your React Native app. Let’s take the scrolling of a music list from the third page on an Android hybrid application as an example. When the user scrolls up to song number 3, the app starts freezing up RAM and performance goes down drastically. This happens because of two reasons: one is that the operations are handled by different parts (native or JS) and passing the data between these parts happens over a bridge.

When Android devices have been running for a long time, the memory leak in ListView seems to be a common problem.

One way to fix this react native performance is by using FlatList or VirtualizedList instead of ListView. Using FlatList in React Native is particularly awesome when it comes to these three things:

  • Needs building
  • This needs to be built. To do that, Pull to Refresh
  • Achieving a seamless experience for your website’s visitors

Application Size and Performance on Android

Although FlatList performance in React Native is exceptional for the majority of use cases, some React Native App Developers still prefer to use a high-performance alternative interface known as SectionList.

It’s been our goal to make the application size small and the performance strong on Android devices. Too much overhead can slow down your app and make it laggy. This is a common problem among Android apps which are heavy on third-party sources, have multiple screens, and rely on other libraries for functionality. The extra resources cause an increase in the app’s size.

To optimize the size of your react native application, you can:

  • You can reduce the size of your app by using ProGuards.
  • One of the many helpful features of JSCore is its capability to create a custom APK file for each CPU architecture. For instance, you could use this feature to create reduced-size APK files that target specific CPUs. The result? When your users download your app, they’ll automatically get the relevant APK file that is optimized for their CPU. This saves space on their device and speeds up installation time.
  • Due to high-resolution and improved viewing quality, images now take up more space than ever. You can reduce the size of your pictures and other graphics by using compression. This is done by converting an image file from a larger file type to a smaller one, like PNG to JPG.
  • When you store JSON data, try to compress it or convert it into static object IDs.
  • Optimize native libraries.

ALSO READ: What Types of Apps Can be Better Build Using React Native?

Native Navigation Components for the React Native Framework in the Android Operating System

Ever since the launch of React Native, its core development team has been experimenting with navigations to optimize performance. We’ve quickly seen some issues emerge with JS and native thread bridge overlay variations that needed optimization.

Have you ever wondered if React Native is the same as a native screen, and what the difference is? Here’s a handy GIF to show you visually:

React Native and Swift are two of the most popular programming languages these days. While they work in different ways, there are many similarities between them. We’ve outlined some of the most important differences so you can choose which one suits you best.

To read all the details on these navigation solutions, keep on reading the next section. If you’ve done or simply want to skip ahead, there are links to every other point.

Navigator is a pure JavaScript navigation component. Though, many developers have found that it isn’t that powerful sometimes in terms of performance.

For example, a web development company based in Taiwan had to ditch the Navigator component for their first client project because Navigator only works for desktop screens.

In this case, the main performance issue comes out when they had to add more features to the app, causing multiple operations to happen on the JavaScript thread.

ReactNavigation was an exact match to the needs of their project, which made it easy for them to easily integrate ReactNavigation with a redux architecture and get better performance.

Navigator for iOS was mainly designed as a native application for iOS. So, when we released Navigator for Android, the real problem we faced was that it wasn’t compatible with any other platforms. This limited its use only to instances when you are working exclusively on iOS as a platform or when your target group is only on iOS, neither Android nor any other OS.

The NavigationExperimental was designed as a highly-customizable navigation system. Unfortunately, the design was not so intuitive for most React Native Developers to wrap their heads around it.

Navigation components mentioned above can still work on your app, even if your app is based on a simpler UI or simpler operations.

One of the largest problems you may encounter is that your app can’t provide a native feel and functionality. This means purely relying on CocoonJS won’t do, which creates issues if your app is based on iOS only.

Infinite Scroll – A better navigation solution for React Native is React Navigation, a JS re-implementation of the native views in iOS and Android.

For routes that need to have a redux-based navigation logic, React Navigation is your alternative to all the other navigation components. It handles browser history and external routing for you, increasing efficiency.

Meet Fuse – Fuse is the world’s 1st and only 100% React-based mobile app framework.

React Native provides some great features to developers, including a Virtual DOM.

Quantum provides a Virtual DOM that allows you to optimize the rendering of JS components and batched asynchronously using their diff algorithm. By batching these changes together, you’ll minimize the amount of data being sent over the bridge, which will improve the rendering and synchronization of both Realm locations.

This algorithm is based on the principle of organizing dependencies, which was originally developed for Javascript-based web applications. Many applications, such as UberEat and F8, have used it to improve their performance by optimizing the message queue.

Also Read: Progressive Web App: A Complete Guide for 2023

The UX’s Update in the Android

React Native offloads all complex functions to the Javascript thread, which causes a delay in updating the app’s user interface.

React Native is experiencing performance issues. Under heavy loads and complex operations, offloading animations doesn’t provide the same level of performance that animation on the main thread would. Right now, this affects animations both navigation and layout-related animations. To fix this problem, React Native’s team has promised to move all animations to the main thread.

The React Native app makes it possible to design a single user interface that will run on both your iPhone and Android device.

When the time to launch your mobile app is slow, you end up with a few inactive users. This is the number one factor that contributes to people churning. One major source of slow app performance and delays in loading times can be caused by React Native, which remains one of the major frameworks for developing mobile apps. A suggested way to optimize this is by taking care of Objects. finalize elements. Finalizers run on a single thread, so every object has to wait until all finalizers have passed through before they can be collected and discarded-generating huge dependencies and slowing down the launch time significantly.

Here is How to Cache React Native Images on Android

Though some npm libraries attempt to solve the caching issue by implementing caching logic in JS and storing images on file systems. However, they often fail to provide the optimal experience we desire to create an awesome app that can make your users delighted.

Image caching on Android devices can be a challenge, especially with libraries installed.

Every time an app’s page is refreshed, this often causes these libraries to fail to load previously-loaded images. If a lot of people are using the website and triggering the caching logic on the backend, then performance could suffer.

If you’re looking for more dynamic caching, react-native-cacheable-image brings placeholder implementations with dynamic caching. React Native Cacheable Image is another improved version of this library that you might want to consider.

If you’re developing an Android app, we recommend using React Native to optimize your images. React Native controls your event-driven architecture, so it’s very important to use responsive images. If you don’t, it can cause your app to suffer from performance issues and errors.

Do you need assistance with your project? We’ve got all sorts of developers available to help, including reactive developers that can be hired on a per-project basis.

What We’ve Learned from Developing an Android App for React Native

This frequently happens because they’re using larger images, which the OS loads for a long time before removing to load other images. To fix this issue, the user is forced to request smaller images from the server.

One way to fix the problem of memory leaking is by using PNG files (instead of JPG) in your app as a static image. This is because reacted native uses the Fresco library to render and display images, which will inevitably result in leaking memory.

There’s a simple fix to this problem – convert your images to WebP format. WebP is an image format that supports both lossy and lossless algorithms for compressing the size of an image. Plus, it can speed up your webpage loading time by 28%.

Rendering the Size of an Image for Different UI Views

React Native apps are brilliant, but there is one huge downside to this powerful app. If a user adjusts the width or height of an image in your app, it’ll be re-cropped and scaled from the original image size; a process that can consume a lot of memory, resulting in an excruciatingly slow loading time for larger images.

To deal with these changes, most developers use the transform: [{scale}] style property to dynamically resize images for different interface screens. Moreover, to make it more memory efficient, you need to implement a custom FadeInImage component that will display a little icon.

This approach exploits the loading and fade-in features in React Native applications.

React Native’s Multi-threading Issues

React Native only has one thread. If one component is being rendered, the other components can’t run at the same time. Whenever React Native renders a member, other components have to wait until it’s finished. Twitch had to move away from React Native after they started implementing live chat features that ran along with a live video feed. They found that the performance became very slow on low-end internet connections because of these bottlenecks.

Twitch is a live broadcasting platform where people can create their channels and broadcast live videos of themselves playing games, visual novels, or anything you can imagine. It also offers interactive chat functionality so viewers can discuss the game being played on a channel they’re watching. Thank you to Twitch.

Build your extension code to avoid multi-threading when threading in React Native. When it comes to multi-threading features, React Native doesn’t offer any support. However, we found developing our extension codes and systems with a heavy focus on system design and maintainability a viable solution. You can easily develop technologies for React Native using the following:

Infinite scrolling is an awesome way to improve performance when working with React. It will make your app load faster, and make your users ecstatic.


One of the major drawbacks of React Native’s Infinite Scroll is that it can be a huge performance bottleneck. React Native provides three different ways to implement infinite scrolling:

ScrollView renders all lists and feeds elements at once

ListView: Boosts the rendering options with pre-defined elements.

If you want to use FlatList, which is available starting at version 0.43 of React Native, it will be necessary to also use the react-native-fetch package and define fetch as a global function to correctly pull in JSON data.

In this article, we’ll go over some common infinite scroll issues that may come up:

1. Scrolling/loading Lags

2. Overly-large Content Blocks

3. Loading Times on Mobile Devices

Loading all content elements at once places a heavy burden on the browser’s cache, which can impact both memory usage and web page performance.

ScrollView: Works better for high-performance Apps, but doesn’t do as well as ListView at loading UI elements

FlatList makes it easy to load UI components and list items on demand with just a few lines of code. It is also known as lazy loading.

Chop, an eCommerce startup from San Fransisco, came up with a solution that was based on Brent Vatne’s experiment for Fixed height infinite lists. They implemented a sliding window with the list in such a way that when the screen is scrolled, the sliding window moves upwards. The items remain fixed at their respective positions. Since this causes the items to stay in one place and not move, it reduces memory usage significantly.

Also Read: Benefits to hire dedicated react native developers from iCoderz

Analyzing iOS Performance Issues

The size of images can be animated for different views of the user interface

Whenever the width or height of an image is adjusted, it is re-cropped and scaled from the original image size. This consumes a lot of memory and the app takes several seconds to load, especially for large images.

Developers typically use the transform: [[scale]] property to dynamically fit the image sizes for different UI views. In addition, you need to implement a custom Fade InImage component to display a tiny shade.

With this approach, React Native applications can quickly project images for different UI views using the onLoad component and the cached fade-in image.

Image Loading in React Native iOS

Whenever your app may run on any kind of slow internet connection, or in a situation where you have larger image grids, like a news app or an e-commerce app, you’ll need to use image placeholders. The below illustration will help you know more about this:

Native React image optimization: Placeholders

React native provides you with a plain user experience that is generally not good for the user.

Another way that organizations like Facebook and Medium combat this is through progressive loading, which works as follows:

Using a tiny thumbnail can create a beautiful animated effect. Try returning the markup of this tiny thumbnail as an <img/> tag in your initial HTML to ensure it is picked up by the browser.

To set up the progressive image component, you’ll first need to specify the thumbnail and wait times in milliseconds.

The entire progressive image loading code is available here.

Filtering Console.log results

This is a re-quote on the article “Console.log() Statements Slow Down Your React Native App”, written by Ross Zampini for

The post discusses console.log() statements, which are included in react native apps to help debug them but can cause performance lag when there are too many calls in your app because they’re synchronous, meaning they might slow down your app. Luckily, there’s a way to remove all those console calls with the babel plugin.

Animations in React Native

React Native gives developers the ability to build simple stock animations, like layout transitions. However, to build custom animations it can be necessary to rely on third-party libraries–like this one!

Third-party APIs and libraries can cause performance and frame rate issues. They also tend to drain your phone’s battery more quickly, which is especially troubling if the app you’re developing requires a lot of graphics processing. One way to combat this issue in React Native is to ensure that the framerate never dips below 60fps.

Animating can be a less-than-optimal experience. These are some issues that generally occur with animations in React Native:

Slow CPU/GPU Frame Rates

Running Out of System Memory

JavaScript on the Thread takes a Time

When you do something that involves heavy computation, it may cause the frame rate to drop. If a new scene has multiple children and computations, for example, there is a higher chance that significant frames will be dropped.

Solving this problem involves using an Animated library with a Native driver. To do this, you can improve your serialization and deserialization time by doing the interpolation work in the native thread. Additionally, you’ll greatly improve the performance of your app as the CPU load gets shifted to just one thread, rather than simultaneously updating all components with mutable Observables.

If a website’s too slow, you might find that there are long navigator transitions.

React Native offers a JavaScript-based thread, which controls animations. When slow data has to be calculated with the animation running on the JS thread, React will lock up and split the loop, which delays/halts rendering to another screen.

If you’re experiencing slow navigator transitions, then the interaction manager will help you significantly. However, if your user experience is suffering way too much, then it may be worth sticking to layout animation.


React Native is a great tool for building cross-platform mobile apps, but it’s important to be aware of the potential React Native Performance Issues that can arise. Now, it’s time to learn how to fix the frustrating performance issues that constantly plague React Native apps. In this article, we’ll share some of the major performance issues and how you can work around them. With these tips in hand, you’ll be able to improve your app’s performance and expand your knowledge of React Native.

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