8 Best Practices to Improve React Native Mobile App Performance

Introduction

The popularity of React Native mobile apps is increasing at an astronomical rate, regarding its capability to create a cross-platform app with a fantastic user experience. Receiving 12.57 percent of the votes in the Stack Overflow Developer Survey 2022, React Native holds the 8th position on the popularity chart.

However, React Native performance is on par with native apps in most cases. For apps requiring a high level of performance, React Native is lagging behind Native in delivering application stability and seamless user experience.

That leads us to question if there is any way we can improve the performance of React Native mobile apps. Therefore, if app performance and user experience have been your priority, the following 8 best practices will provide you with a working framework to optimize and improve your app performance!

Why Is App Performance Important?

Let's put it this way, nobody likes underperforming apps. With apps demanding full advantage of the device's features and capabilities yet built on React Native, slow load and under-performance can be persisting issues.

Poor application performance can directly impact the user experience. Slow-loading apps can lead to frustration and poor engagement, and ultimately result in an increasing churn rate. Ultimately, it can affect your revenue due to a decrease in in-app purchases when users no longer use your app.

Issues with app performance can also harm a brand's reputation since the customer's perception of the brand is directly affected by their initial impressions when engaging with it. This can further bring about negative reviews and ratings, which can have a negative impact on a brand's image.

Additionally, statistics show that increasing the customer retention rate, even by just a margin of 5%, can increase profits by 95%. And what's more, most companies agree that retention is cheaper to execute than acquisition. Therefore, losing a customer due to poor application performance or stability is preventable and should never happen.

8 React Native Best Practices: A Framework to Enhance App Performance

Now that we are aware of how critical app performance is to the growth of a business, let's see how we can improve it. If you have been familiar with popular techniques such as code optimization, reducing bundle size, or using virtualized lists, yet the issues keep persisting, you might need to change the current approach.

Therefore, regardless of what market or industry you operate in, here are 8 best practices that you can adopt as a framework to resolve React Native mobile app performance issues.

Avoid guesswork

First of all, when you deploy and work on any React Native mobile app, your team should avoid as much guesswork as possible. Poor assumptions can lead to useless work. Therefore, project managers, product owners, and developers should make decisions based on data. Otherwise, it would be a waste of time trying to fix unidentified issues.

There are no fixed formulas or techniques for every React Native mobile app. And your team can not handle app performance issues by applying everything recommended in an online article. As said, your team should initiate the improvement process by identifying root causes based on collected data points. There can be several factors affecting your app performance and you cannot resolve them all at once. It can take time to improve and it should be an ongoing process.

Define project phases

In short, it is when you use collected data to define problems, project goals, optimization opportunities, and customer deliverables. This is a structured approach that ensures your team is going in the right direction.

With clearly-defined phases in mind, your team will know exactly what to do, what goals to achieve, and what should be the priority during the process. This will also help establish a groundwork for later effectiveness assessment as you launch a new version of your app.

Conduct a user analysis

You can start by listening to the voice of the customers. This specific term describes the customer feedback about their experience and expectations for your React Native mobile app. With such input, you can better understand customers' needs, preferences, and ongoing problems that they are facing while using your app.

Common methods to collect the voice of the customers include:

• Building customer engagement program;
• Designing in-app feedback form;
• Evaluating ratings and comments of users about the app;
• Performing user path analysis

You can start by listening to the voice of the customers.

However, user feedback can be vague and difficult to measure. As a result, we will need to transform collected data into something measurable and specific. The measurable elements of a product or service that present customer expectation level are called Critical to Quality (CTQ).

For example, you receive feedback that says “I want a fast checkout process”. After analyzing a cluster of components, you can define CTQ performance requirements as follows

• A low number of steps in the check-out flow;
• Ability to use native payments;
• Quick server response;
• A low number of server errors;
• Smooth animations and transitions between screens (more frames per second a.k.a FPS & fewer re-renders).

Design measurements and metrics

As your team proceeds to work on the project, you will need a set of measurements and metrics. It's essential to assess the extent of the issues and quantify them with the data.

It's all about collecting as much data as possible to get a more well-rounded picture of the existing performance issues on your React Native mobile apps. Let's say you understand the need to optimize your app for more frames per second & fewer re-renders, yet you have no clue what number to propose. It's where the data comes into play.

When you have a strategy to collect each data point (i.e Min. FPS per checkout flow, min. FPS on product catalog, app startup time, the average time to check out, etc.), you know what elements are part of the problem, and how much optimization can be done.

At this point, you can create a plan where you describe the data, select and validate the collecting method, assign team members, and prepare a data repository.

It's essential to assess the extent of the issues and quantify them with the data.

Use profiling tools

With a data repository ready, the next question is whether to profile JavaScript or Native. While performance issues in React Native mobile apps often stem from the JavaScript side, the profiling process should be a mixture of both in most cases.

One of the most helpful tools you can use for the profiling process is React Profiler API. It's a built-in API that helps developers measure the number of renders and the amount of time necessary to render these components. This is an effective tool to identify unnecessary rendering. While it’s mostly designed to work in development mode, you use its special version of React to measure production build.

Another tool for the profiling process is a library called react-native-performance. This a profiling tool for both React Native and JavaScript. It’s an implementation of the performance API of React Native that lets you place native markers in the code and measure the execution time. Additionally, you can use it to verify the network request and export several useful native markers. Most of these features can work in both development and product. You can use a flipper plugin to visualize your output.

Be cautious of measurement variations

There are several aspects to consider during the measurement process, especially when you are using a wide range of tools. Due to the variety of environments where you can run your React Native mobile apps, you should be careful and precise when profiling.

A myriad of factors to consider include platforms, operating systems, forms, etc. Even if the app is running on the same device, there are many external factors that can impact its operating capabilities.

Test your hypothesis

Once the fixes and updates for your native mobile app are ready, it's time to test your hypothesis. As mentioned previously, there can be a myriad of factors contributing to the poor performance of your apps. You can not evaluate if your hypothesis about the root causes is true or whether the optimization effort is worth it without testing.

There can be a myriad of factors contributing to the poor performance of your apps.

As you design the test and interpret the results based on a set of predefined goals, you are able to conclude the impact of certain optimization on the final results. From there, you can make an improvement decision and decide on the official update of your React Native mobile app.

Keep app performance under control

Last but not least, you have to learn how to keep app performance under control. As your team releases the official update and the app starts receiving ratings and good feedback, you have to ensure that the issues are completely resolved.

If you look at the app's performance over time, you can observe a cycle where arising issues and optimization come along with feature development. There is a also high level of complexity while developing any app – a hindrance to any optimizing effort. Therefore, if you do nothing to keep the app performance stable and under control, issues will happen at some points.

You can initiate a control plan with

• Focal points;
• Measurement characteristics;
• An acceptable range for each issue indicators’
• Testing frequency;
• Defined procedures indicating what to do when spotting issues.

The most important aspect of the entire control phase is to monitor regression. A few suggestions include

• Reassure – a tool to monitor app performance on CI or local machine;
• Firebase – a tool to gain insight into the key performance characteristics;
• Sentry – a tool to track app performance, measure metrics, and display the impacts of errors.

Conclusion

Without a proper framework to execute optimization efforts, implementations may not work as effectively as you expect. By adopting these 8 React Native best practices outlined in this article, you can improve the performance of your React Native app and provide a better user experience for your customers.

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