Understanding the underlying performance architecture of Flutter and React Native is key for developers looking to build high-performance applications in 2025.
Flutter’s Engine and Rendering Pipeline: Skia and Ahead-of-Time Compilation
Skia rendering engine is the core of Flutter’s performance. It draws every single pixel of the interface directly using Skia. That’s how Flutter is able to bypass the platform-specific UI frameworks (like Android’s View hierarchy or iOS’s UIKit), handing over developers the full control over the rendering process.
By 2025, Flutter’s rendering pipeline would be further optimized to take advantage of hardware-accelerated graphics and multi-threaded rendering. It makes it possible for Flutter to offer high frame rates even in complicated apps with lots of motion.
The way Flutter works with threads is as follows:
- UI Thread: The UI Thread handles events that come in from the user and sends data to the GPU so that it can be rendered.
- Raster Thread: UI elements are turned into pixels by the GPU thread and sent to the screen.
Ahead-of-Time (AOT) compilation is used for production builds with the Flutter Engine. It means that the Dart code has been turned into machine code that runs on ARM or x86. There is no longer a need for a runtime translator. It cuts down on starting time and speeds up performance.
Additionally, Dart’s tree-shaking removes unused code, making the final app package smaller and more performant.
By skipping native UI components, Flutter is able to achieve uniform performance across platforms. It offers smooth animations at 60fps or even 120fps on high-refresh-rate screens. This method works great for apps that need a lot of graphics, like mobile games.
For many years, React Native used a JavaScript bridge to let the JavaScript thread (which runs business logic) and the native thread (which renders UI components) talk to each other.
This two-tiered architecture introduced a layer of latency. It usually happens when rapid communication between the two threads is needed.
To address this, the introduction of the Hermes engine in 2020 laid the groundwork for major performance improvements. By 2025, Hermes is now the default JavaScript engine for React Native.
It has been tweaked to make the bridge's overhead as small as possible. Hermes runs bytecode directly, which speeds up starting times and uses less memory.
Along with Hermes, React Native has added Concurrent Rendering, which was inspired by React's Concurrent Mode, to make processes run faster when they are complicated.
It makes React Native render UI components incrementally, instead of waiting for the entire render tree to complete. By breaking rendering tasks into smaller, manageable chunks, concurrent Rendering enables smoother animations and prevents UI lags.
In 2025, which one you choose should rest on the skills of your team, the needs of the project, and the platform you want. Flutter is great at making UIs that are flexible and fast. React Native has a huge community, and it's simple for JavaScript developers to use.
Get in touch with our tech experts right away to find out more and get help choosing the best framework for your project
