Useful Tips to Optimize Your React Application

Web application performance issues are not new. Developers have faced these issues for a long time, so as soon as a new language emerges, developers start facing such difficulties.

In terms of language, React boasts of a fast DOM. And it is fast to the point where it sometimes renders a lot of irrelevant parts of the tree. This causes a UI glitch, and sometimes developers are hesitant to continue using the language.

In this article, we will examine some of the best ways developers can easily solve performance-related issues in React-based web applications. In terms of rendering performance, react is one of the best UI frameworks.

Even though its virtual DOM is popular for effectively rendering components, small to medium-sized web apps can still encounter performance issues.

How UI Is Rendered In React?

DOM (Document Object Model) is React’s basic document structure that updates your UI. In basic terms, we can say DOM is a tree-like structure of nodes and objects.

It is the only node from the JavaScript prototype chain that determines styles, and properties, and manipulates the individual nodes in React. HTML on the other hand is not the root of the DOM.

In React, DOM is simply a way to access, update, and manipulate HTML elements. The DOM in React can assist in rendering a webpage but doesn’t have the intelligence to keep the track of each node and component which is being updated.

With DOM, you will end up updating an entire list as that list will be re-rendered when updating one of the 10 items on your SPA (Single Page Application).

To make this work, React has a concept known as the Virtual DOM. It is a kind of local copy of the HTML DOM that React uses to render the UI.

By comparing the real DOM with the virtual DOM, React creates a copy of the UI when the user interacts with it, and this virtual copy is then updated. This ensures that only the item that needs to be updated is affected.

What’s BAD about Virtual DOM in React Js?

We discussed the positive aspects of Virtual DOM in the previous section. Now we will discuss the negative aspects, which are solely responsible for a lot of React’s performance issues.

As a part of its architecture, react makes use of a diff algorithm to reduce the amount of work at nodes. However, this algorithm in itself is imperfect. Rather than rendering only the relevant components, React renders the entire subtree.

They are called wasted renders because they consume unnecessary CPU and memory resources when left idle in a React application and this can be fatal.

Ways Of Optimizing Useless Renders In React Application:

Despite its amazing potential, React Virtual DOM generates many performance issues by rendering unnecessary components in the DOM tree. This makes even a medium-sized app perform slowly because it unnecessarily renders components.

Input on the second todo raw causes the first todo raw to keep flashing on the UI in the response to keystrokes. This indicates that React is updating the first todo raw while the input.

React is unaware that the first todo raw has not changed, so it saws a waste of resources. These unnecessary renders are called “wasted” renders.

If you have a large complex React application, where states abound and newer updates are constantly coming in, what will happen to the performance of your project? You bet there will be serious performance issues.

1) Immutable.Js Enables React to Prevent Wasteful Renders

It’s your job to specify whether the component should be re-rendered to reflect the current state and new properties in the ShouldComponentUpdate method.

The alternative would be for React to leverage the diff algorithm for this decision, which would be computationally expensive, Recurrent calls to this method would slow your React app down dramatically.

Furthermore, if your component is re-rendered and its properties change, you will need to compare the old and the new props. However, this comparison is complicated.

The immutable data structures do not change or you can say they can not change. This is where immutable data comes into play.

A React app that uses immutable data can quickly compare direct object references, instead of parsing through deep trees. Immutable data eliminates this problem.

2) Using the Right Component Keys to Optimize React List Performance

The key attributes determine which elements can be reused in the next rendering phase. Consequently, dramatic lists can be updated with these keys.

The new element is updated by comparing its keys with those of the previous element. Additionally, rendering components with a new key may also enable the un-rendering of components with keys that are no longer needed.

When developers render a list, they usually treat a given item’s index as a key, and this leads to performance issues. Rather than allowing the user to type the third item, clicking “Add Item” will show the text of the previous item.

The third item in this example illustrates the use of the index of items in place of key components, causing the previous component to be rendered again.

Your lists will perform better if you use the key attributes you identified. In addition, remember that each component of your list should have its unique key value.

3) “Why Did You Update” Library Detects Unnecessary Rendering Of Components

The “why-did-you-update” library, which hooks into React and attempts to detect potentially unnecessary component renders, can still be used if you’re not satisfied with the results of the React performance tools.

As soon as the library is in an active state, it will inform you if a piece of state is causing your component to update, which is not the case in reality.

4) Using Purecomponent Reduces Rendering By Delaying Unnecessary Animations

The Pure Component class, which is a more performant version of the React component class, may be able to help if you’re not seeing any performance gain using shouldComponentUpdate.

As a result of the use of Pure Component, the application’s performance increases significantly. Components in React are exactly like their counterparts in React except that the shouldComponentUpdate method is automatically handled by them.

5) Improving The Performance Of React 16 By Locating Wasteful Renders

In most cases, it is up to the developer to determine which renders are causing your application to slow down. However, in a React 16 system, how can you identify rendered renders that aren’t needed?

Fortunately, React performance tools chrome extension comes in handy for applications like yours. React 16 is the only version of these tools that works blazingly fast.

Checking the User timing accordion will allow you to view all the logs related to heavy CPU usage and will help you analyze your profile. Identifying the areas in your app with slow rendering will help you improve your app.

6) How Code Splitting Improves App Loading Time

You should only load the code that your users require upfront to make a webpage load faster for them. It makes no sense to load the admin panel code when you want the user to view the landing page, especially when it comes to single-page apps (SPA).

Code splitting can be applied to this situation. You can dramatically improve your app’s performance by “lazy-loading” only the things that are currently required by the user by code-splitting it.

Pinterest reduces the size of its bundles from 650KB to 150KB using the code-splitting technique, which divides JavaScript bundles into three categories.

As a result of Codesplitting, Pinterest’s app is now loading in 6.5 seconds rather than 23 seconds following a small reduction in bundle size. The CommonsChunkPlugin allows you to split your code into several files using Webpack.

When it comes to bundled code, you could use ReactLoadable to split it down for lazy loading instead of using a web pack.

7) Prevent Unnecessary Renders With ShouldComponentUpdate

Small but sufficient changes in most mobile apps can help resolve performance-related issues, and as a result, increase the speed of the app.

A small but impactful change to your React app is the shouldComponentUpdate method, which appears to be small but provides enough measurable and perceivable performance improvement.

If the state of a component does not change, you can use the shouldComponentUpdate lifecycle hook to prevent React from redrawing it.

As an example, imagine a list that consists of many components that are nested in a complex structure, and one component changes. By rendering the unnecessary components from the list, your app will eat up additional resources.

You can turn React off of all components except for the one that has changed by implementing shouldComponentUpdate. By correctly implementing the shouldComponentUpdate method, Twitter engineers increased performance by 10 times.

It does not mean that shouldComponentUpdate will also work in your case if Twitter succeeds with React and achieves faster speed. What are some ways to identify when you should use shouldComponentUpdate in your React app?

Simple… If you saw a significant improvement in your app’s performance from it, then it was the right change.

If it does not, then your React components will only slow down. The maintenance of your code using shouldComponentUpdate can be difficult, therefore it can also result in a lot of bugs.

8) By Using React Virtualized List, You Can Optimize List Rendering

Virtual rendering becomes important in this case. This program lets you render just 30 components instead of rendering all of them. You can also render 40 or 10 components. The result will be a small subset of components, regardless of how many there are. As a result, performance will be greatly enhanced.

React Virtualized List uses virtual rendering techniques to make your UI performant every time your list of data is large. This library gives you the power to make your UI responsive even when the list of data is large.

9) Tuning React Performance By Fixing Unnecessary Renders of Components

Components can be rendered unnecessarily every time their state changes. Often we render all of the components’ children even when they don’t need to be rendered at all.

10) Identifying Problematic Bundles For A React-based PWA

Identifying problematic chunks of code in your production build is the first step in optimizing the bundle size of React apps.

The WebPack Bundle Analyzer plugin can help you analyze your build dependencies if you are using Webpack to streamline React bundling.

With the help of the Webpack bundle analyzer plugin, Pinterest identified tons of redundant code in their build and moved it from the async chunk to the main chunk, which resulted in a 90% reduction of the lazy-loaded chunk size.

Conclusion

I hope you have a clear idea about how you can optimize the react app. Hopefully, you can now solve React performance issues and enhance the performance. You can still connect with us for any query related to react js web development or services. We will be happy to answer you.