Oshini Cooray
3 min readMay 22, 2022


Optimizing application performance is critical for developers who want to keep users on an app and interested.

According to Akamai study, a second delay in load time can result in a 7% drop in conversions, making it critical for developers to create apps that function well.

By default, React applications have an extremely quick user interface. Developers may, however, run into performance concerns as a program grows.

We’ll go over five important strategies to improve the performance of a React application in this post, including pre-optimization techniques. Among them are:

Techniques for react pre-optimization

We must first understand how React refreshes its UI and how to measure an app’s speed before we can optimize it. This makes resolving any React performance issues a breeze.

Let’s begin by looking at how React UI updates.

Understanding how React’s UI is updated

React provides a virtual DOM for the component’s element tree when we create a displayed component. React now recreates the virtual DOM tree whenever the state of the component changes and compares the result to the previous render.

The DOM is then just updated with the altered element. This is referred to as diffing.

Because manipulating the actual DOM is expensive, React leverages the concept of a virtual DOM to reduce the performance cost of re-rendering a webpage.

This is beneficial since it reduces the time it takes for the user interface to render. However, if not properly maintained, this approach might slow down a sophisticated app.

A state change in a React component produces a re-render, as we can see above. When state is sent down as a prop to a child component, it re-renders the child and so on, which is good because React must refresh the UI.

The problem arises when the state change has no effect on the child components. To put it another way, they don’t get any props from the parent component.

Despite this, React re-renders the child components. As a result, as long as the parent component re-renders, all of its child components re-render as well, whether or not a prop is sent to them; this is React’s default behavior.

Profiling the React application to identify bottlenecks

The Profiler in the React DevTools allows us to measure the performance of our apps. Every time our application renders, we can collect performance data there.

The profiler keeps track of how long it takes a component to render, why it’s rendering, and other details. We can then inspect the affected component and make the necessary adjustments.

Take use of the Production Build.

Make sure you’re testing using the minified production build if you’re benchmarking or having performance issues with your React apps.

React comes with a lot of useful warnings by default. These alerts are really helpful throughout development. They do, however, make React bigger and slower, so make sure you use the production version when deploying the project.

Installing React Developer Tools for Chrome will help you determine whether your build process is set up appropriately.

Long Lists Are Virtualized

We advocate adopting the “windowing” technique if your application renders extensive lists of data (hundreds or thousands of rows). This strategy renders only a tiny portion of your rows at a time, reducing the time it takes to re-render the components as well as the number of DOM nodes created.

Popular windowing libraries include react-window and react-virtualized. They come with a number of reusable components for displaying lists, grids, and tabular data. If you want something more specialized to your application’s specific use case, you can design your own windowing component, as Twitter did.