Best Performance Optimization Tips for Your ReactJS App

Encountering performance-related issues is a common factor for web applications. Whenever a new language originates, or the existing one undergoes an upgrade, developers and business owners end up facing complications in their applications. The same is the case with ReactJS. 

The technology boasts of its fast DOM; it is fast in a way that sometimes it ends up with many irrelevant components rendering the DOM tree. 

This often poses a glitch, which complicates the application. Therefore, successful entrepreneurs always hire ReactJS developers and keep them handy if any element goes haywire in the application. 

This helps avoid unwanted issues and ensures a smooth UI/UX. 

How is UI rendered in a React app?

The rendering of UI in ReactJS is based on the updation of the DOM ( Document Object Model). The DOM is built in a tree-like structure consisting of nodes and objects. In ReactJS, the root of this DOM is not HTML; instead, it’s just a single node from the prototype chain of JavaScript; this enables it to get the function of calculating properties, styles, or manipulating individual nodes. 

In layman terms, the DOM in React decides how you update, extract or manipulate the HTML. Although the DOM renders each page, it fails to keep track of each component or node that is updating. 

Therefore, in a regular DOM, if you wish to render 10 SPAs, all the elements and nodes will automatically be updated, taking longer. 

However, ReactJS uses the Virtual DOM. It is the local copy of HTML DOM, built in React.

The Virtual DOM would compare the changes in the React DOM and update only the required elements. Therefore, taking less time and showcasing better performance. 

Top performance tips for React apps: 

Even though the Virtual DOM concept followed by ReactJS is incredible, it still creates performance issues due to the irrelevant component rendering in the DOM tree. This can make even a medium-sized application lose its performance. 

However, there is nothing to worry about. 

We have amalgamated some of the best tips to avoid unnecessary DOM elements and give your React application the boost it deserves. 

  • Detect wasted renders with React performance optimization tools: 

In most cases, you will have to look for ReactJS programmers for hire to identify the wasted renders in your React applications; these renders make your applications slow and result in performance issues. 

But the question is, how to detect these renders? 

You can take the help of React performance tools available in Chrome extensions. However, currently, these tools only work excellently with React 16. You can identify the slow-performing parts of your application by checking user timing and analyzing all logs related to heavy CPU usage. 

  • Use “why did you update” library:

Another way of detecting the unnecessary elements of your React application is by using the “why did you update” library, which can hook into React and see the potential unnecessary component renders in the application. Once the library goes into your application and becomes active, it sends alerts into your console every time a part of your React app makes your component update. 

  • Use “PureComponent” for improved performance: 

If you fail to get performance in your application, you must try using Pure Component; it is a better performance version of the React component class. If you use the Pure Component, you can experience a significant increase in your app’s performance since it reduces the number of render operations. 

If you have used the component class in React, using the Pure Component would not be a difficult task since both work similarly. 

  • Use Immutable.js to prevent wasted renders: 

We suggest you should hire ReactJS developers to define the shouldComponentUpdate method. While your developer does that, s/he would have to tell if the components require re-rendering to reflect the states and properties. 

In case it is not done, React will leverage a different algorithm for the decision. This may be computationally expensive. 

The ideal way to use shouldComponentUpdate is to create it to be more lightweight. 

Recurrent calls in this method would pose a severe problem in the performance of the application.

Optimizing the loading time for the PWA React application: 

In time, as your developer codes in ReactJS, you might end up making wrong async calls that can add up to the bundle size of the Progressive Web Application built in React. The increased bundle size can cause lag of loading. 

However, the tools given below can help enhance the loading time of the React application. 

Check them out: 

  • Identifying problematic bundles: 

The initial step of optimizing the React application is identifying the problematic parts of codes in the production build. 

If you utilize webpack to execute easy bundling in ReactJS, you can also try the webpack build analyzer plugin to analyze the build dependencies. 

A great example of the plugin would be Pinterest; the website was able to identify many duplicate codes using the webpack bundle analyzer plugin. They moved the duplicate codes from their async chunk to the main chunk; this resulted in a 90% decrease in the size of the lazy load chunks.

Here are some excellent plugins you can use to minimize the load on your website: 

  1. Compression webpack plugin
  2. Ignore plugin
  3. Uglify plugin
  4. Dedupe plugin
  • Code splitting for reduced loading time: 

If you need your users to get your content faster, it is wise only to load the specific content your user requests. 

Especially when it comes to Single Page Applications (SPA), it makes no sense to load the admin panel if your user needs to view the landing page. 

This is where code splitting comes to the rescue. Code-splitting your ReactJS application will “lazy load” just the components currently required by your users. This can result in a significant increase in the performance of your application. 

Thus offering a better user experience and intuitive UI. 

However, to execute the code splitting in the desired manner, you would have to look for ReactJS programmers for hire and brief them about your requirements. 


Countering issues is inevitable when it is about web applications. All you can do is be prepared to solve them the moment they reach you. And how is that possible? Well, if you have an app in any other technology, this article may not help. However, if you have a ReactJS based application, you are in luck. 

Follow any of the tips mentioned above. And you will be able to successfully counter all your ReactJS rendering issues and bring out a high-performing application to your users. 

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