Question

How to optimize the re-rendering of large amounts of child?

I have a React project with many child components. My child components are re-rendered whenever its parent component re-renders. As far as performance goes, this is slowing down my app. How could I optimize or prevent such unnecessary re-renders to improve performance?

Answer 1

When dealing with components that render many child components, it’s essential to optimize re-renders to prevent performance bottlenecks.

For that we have some effective strategies :

1. React.memo : We can use React.memo to memoize the child component. This means the child will only re-render when it props change , effectively preventing unnecessary renders.

const Child = React.memo(({Ram}) => {
return <div>{Ram}</div>;
});

• Custom Memoization : We can also implement custom memoization logic using useMemo or useCallback for more granular control.

1. useMemo : useMemo can prevent unnecessary re-rendings and optimize the performance.

• By memorizing the result of a function and tracking its dependencies, useMemo ensures that the process is recomputed only when necessary.

1. Virtual Lists : For large lists of items , virtual lists can significantly improve performance by rendering only the visible items. Libraries like react-window or react-virtualized can help implement virtual lists.

2. State Management :

• Context API: Use the Context API to share state between components without passing props through multiple levels.

• Redux : Consider using state management libraries like Redux for complex state management scenarios.

1. Lazy Loading : For large components, use code splitting to load them only when needed, improving initial load times.

• React.lazy : This built-in feature allows us to import components dynamically

import React, {lazy , Suspense } from 'react';

const My = lazy(() => import('./My'));

function App() {
return (
<div>
<Suspense fallback={<div>Loading...</div>}>
<My/>
</Suspense>
</div>
);
}