Both Flutter and React Native are popular frameworks for cross-platform mobile app  development. 

What is Flutter? 

A properly chosen framework partly defines the overall success of the project. Flutter  framework brings cross-platform development to the next level. It provides many features  that we’ll look at a bit later. And for now, let’s find out what Flutter is, what the benefits  of Flutter app development are, and why everyone in the IT community keeps talking about  it. 

Flutter is an SDK – Software Development Kit. Some people confuse the concept of SDK  with the idea of a framework. However, a framework is basically an almost ready-made  library with some gaps that you fill with your code, so the app works. In turn, SDK is a  much broader notion that includes libraries, frameworks, and other tools. 

Back to Flutter. It is an SDK (including framework) developed and launched by Google.  It’s based on Dart programming language, which is created by Google as well. Initially, it  was made for building web apps, but later, it significantly evolved and is now used for  mobile and desktop solutions. It is an object-oriented language, so the transition from other  object-oriented programming languages will be smooth. 

What is React Native? 

React Native is a framework built on JavaScript. It is designed for creating solutions for  different operating systems. To be implemented on iOS and Android with the same code,  React Native uses a so-called bridge. It builds the connection between the written code and  native APIs. 

It provides many tools that allow you to estimate how “native” an app feels through the  whole development process. For this, React Native renders real native components, so it is  easy for you to keep track of your progress. 

 The first reason why developers choose React Native is that it is easy to learn due to its  architecture. Besides, there has formed a great supportive community for the years React  Native is on the market. Also, it provides specialists with lots of useful tools because  Facebook backs it, and new features are continually introduced. One more reason why  React Native app development is the right choice for both aspiring developers and  professional ones is that it reminds other environments for hybrid development. 

While many other cross-platform frameworks rely on the web view, React Native uses  rendering APIs. It helps to achieve better performance with a native look at the same time.

Apart from the mentioned advantages, we have all upsides of hybrid development in  general. They are reduced development time and cost, more straightforward  implementation and easier updates, etc. 

Performance — Which is More Effective? 

In this article, the team created a demo app with the same functionality using native  languages, ReactNative, and Flutter. Afterward, they measured performance, graphics,  CPU load, and memory usage on both Android and iOS devices. According to their tests,  native apps provide the best performance, followed by Flutter with a little lower  benchmarks and then React Native with slightly worthwhile results. To explain this output,  let’s take a look at the architecture and how does react native and flutter work.

Flutter VS React Native: Architecture and operational principles 

The execution of the source code on React Native requires a “bridge” from the JavaScript  (JS) code to the device’s native environment. This bridge allows these two environments  to communicate and exchange data. In a nutshell, the bridge is an interpreter that translates  JS code to the device’s native programming language and vice-versa. Unfortunately, the  bridge is an additional agent in this toolchain that requires extra time and resources for  processing and usually creates a bottle-neck in react-native applications. 

In contrast to this, Flutter, whose programming language is Dart, can access native features  of the mobile device directly without any additional interlayers. Thus it compils quicker  and consumes fewer resources to execute the code. That results in the instant start-up of  the application, faster performance, and the ability to process multiple threads and  complicated animations with less load on the device. Flutter is a good React Native  alternative that processes sophisticated algorithms and complex graphics quicker and more  efficiently. they measured performance, graphics, CPU load, and memory usage on both  Android and iOS devices. According to their tests, native apps provide the best  performance, followed by Flutter with a little lower benchmarks and then React Native  with slightly worthwhile results. To explain this output, let’s take a look at the architecture  and how does react native and flutter work.

React Native

Flutter

So, right off the bat I’m surprised about the significantly higher CPU utilization on the  Pixel. so my natural assumption would be that CPU utilization for the same application  would be lower, not higher. I can see why the memory usage would be higher, since there’s  more memory on the Pixel and Android follows a general “use it or lose it” strategy for  holding onto memory. I’m interested in hearing why the CPU usage would be higher if  anyone in the audience knows! 

The second interesting take away here is that Flutter and React Native have diverged  heavily in their strengths and weaknesses vs their native counterpart. React Native is only  marginally more memory-hungry than the native app, while Flutters memory usage is  almost 50% higher than the native app. On the other hand, the Flutter app came much closer  to matching the native apps CPU usage, whereas the React Native app struggled to stay  under 30% CPU utilization.

Conclusion 

I feel confident in saying that Flutter app will perform better than React Native app. We  would definitely not recommend using React Native in a very CPU heavy operation, while  Flutter is a great fit for such tasks from both CPU and Memory standpoint. We tried to  bring as much transparency into the process as each app to get tested and a single set of  tools to measure the performance, and I hope you liked the result. Yet again our mobile  team are happy to receive and carry all the burden of your feedback and suggestions.