8 React Js performance optimization techniques YOU HAVE TO KNOW!

Summary

In this video, the creator highlights 8 essential React performance optimization techniques to boost application efficiency. The strategies covered include list virtualization for large datasets, lazy loading images, memoization to avoid redundant calculations, throttling and debouncing for event handling, code splitting for faster loading, React fragments to reduce DOM nodes, web workers for offloading heavy tasks, and the `useTransition` hook for smooth state updates. These techniques help improve load times, responsiveness, and overall user experience in React applications.

Takeaways

• 😀 **List Virtualization**: Only render visible items in a list to optimize memory and performance, using libraries like `react-virtualized`.
• 😀 **Lazy Loading Images**: Load images only when they become visible in the viewport to reduce page load time and unnecessary DOM nodes.
• 😀 **Memoization**: Use `React.memo`, `useMemo`, and `useCallback` to avoid unnecessary re-renders and expensive recalculations, improving performance.
• 😀 **Throttling Events**: Limit the number of times a function is executed within a given time frame (e.g., resizing a window) to prevent overload.
• 😀 **Debouncing Events**: Delay function execution until the user has stopped interacting (e.g., typing in a search input) to avoid excessive calls.
• 😀 **Code Splitting**: Split your large JavaScript bundle into smaller chunks to load only necessary code, improving initial load times.
• 😀 **React Fragments**: Use React Fragments to group elements without adding unnecessary DOM nodes, reducing the DOM tree size.
• 😀 **Web Workers**: Use background threads (Web Workers) to handle heavy computations and tasks, preventing UI blockage.
• 😀 **`useTransition` Hook**: Mark less critical state updates as non-urgent, allowing them to run in parallel and keeping the UI responsive.
• 😀 **Performance Balance**: Always consider performance optimization techniques, especially when leveraging React's powerful features, to avoid negative impacts on speed and efficiency.

Q & A

What is list virtualization in React and why is it important?

List virtualization, also known as windowing, is a technique where only the visible portion of a large list is rendered at any given time. This conserves memory and improves scroll performance, especially when dealing with massive amounts of data.

How can lazy loading images improve performance in a React application?

Lazy loading delays the loading of images until they are visible in the viewport. This reduces the number of DOM nodes created upfront, lowers initial page load time, and improves overall performance.

What are the three memoization techniques in React, and how do they differ?

The three memoization techniques are: React.memo (prevents re-rendering of a component if props haven't changed), useMemo (caches results of expensive computations), and useCallback (caches function instances to prevent unnecessary child re-renders). They differ in what they cache—components, computed values, or functions.

When should you use throttling and debouncing in React?

Throttling should be used when you want to limit function execution to a fixed interval (e.g., window resize events). Debouncing should be used to delay function execution until the user stops performing an action (e.g., finishing typing in a search input). Both reduce unnecessary computations.

What is the purpose of code splitting in React?

Code splitting divides a large JavaScript bundle into smaller chunks, which are loaded only when needed. This improves initial page load times and ensures users only download the code necessary for the current page.

How do React fragments help improve performance?

React fragments allow grouping of multiple elements without adding extra DOM nodes. This results in a smaller DOM tree, fewer unnecessary elements, and improved rendering performance.

What problem do web workers solve in React applications?

Web workers run scripts on a separate background thread, allowing computationally intensive tasks to execute without blocking the main JavaScript thread. This keeps the UI responsive even during heavy processing.

How does the useTransition hook improve React application performance?

The useTransition hook allows certain state updates to be marked as non-urgent, so they don’t block rendering. This ensures smoother UI updates when some state changes require heavy computations.

Why is combining React.memo with useCallback often recommended?

React.memo prevents unnecessary re-renders if props haven’t changed, while useCallback ensures function instances remain the same across renders. Combining them avoids child component re-renders when passing functions as props, improving performance.

What libraries or APIs can be used for lazy loading images in React?

Lazy loading can be implemented using libraries such as React Lazy Load or natively with the Intersection Observer API combined with React's useEffect hook.

Can list virtualization be used for tables as well as lists?

Yes, list virtualization can be applied to tables or any component rendering a large number of items. It ensures only visible rows or items are rendered, improving performance for large datasets.