When building React applications, API calls are often at the heart of the data flow. Whether it’s fetching product listings, user profiles, or search results, a slow API response can ruin the user experience—no matter how beautifully the UI is crafted. Users expect instant feedback, and even a delay of a few seconds can lead to frustration or bounce. So, the question is: how do you make your API calls faster in a React app?
The good news is that while you can’t always control the backend speed or network latency, there are multiple strategies you can implement on the frontend to make your API interactions feel faster and, in some cases, actually reduce the wait time significantly. In this blog, I’ll walk you through a number of techniques and best practices that I’ve used to optimize API call performance in React apps.
Use Efficient APIs
Before optimizing the frontend, ensure the API itself is efficient. Ask yourself: is the backend sending unnecessary data? Is it paginated? Are you making multiple round-trips when one would do?
If you have any control over the backend or are working closely with the backend team, make sure:
- The API supports pagination, filtering, and sorting on the server
- You fetch only the required fields instead of full objects
- You avoid N+1 query problems on the backend
- The server supports compression like GZIP or Brotli
Once the backend is optimized, let’s shift focus to the frontend strategies in React.
Avoid Unnecessary Requests
Making the same API call repeatedly is a common performance mistake. If the data hasn’t changed, why re-fetch it?
In React, this usually happens when components re-mount or when useEffect dependencies are misconfigured. To prevent this, ensure that your useEffect has proper dependency arrays. For example:
useEffect(() => {
fetchData()
}, []) // Only runs on mount
You can also store fetched data in a state management solution (like Redux, Zustand, or React Context) and reuse it across components instead of calling the same endpoint again.
Debounce Rapid Requests
If your API call is tied to a user typing into an input (such as a search field), every keystroke might trigger a request. That’s wasteful and slow. Debouncing delays the API call until the user stops typing for a specified amount of time.
Here’s how you can debounce in React using useEffect and setTimeout:
useEffect(() => {
const handler = setTimeout(() => {
if (searchTerm) {
fetchResults(searchTerm)
}
}, 500)
return () => clearTimeout(handler)
}, [searchTerm])
You can also use utility libraries like Lodash’s debounce function for more robust handling.
Show Optimistic UI
While this doesn’t technically speed up the API call, it feels faster to the user. In an optimistic UI approach, you update the UI before the API call is completed.
This is especially useful for actions like liking a post, adding an item to a cart, or toggling a setting. For example:
const [liked, setLiked] = useState(false)
const handleLike = async () => {
setLiked(true) // Optimistic update
try {
await api.likePost(postId)
} catch (error) {
setLiked(false) // Revert if API fails
}
}
Optimistic UI gives users the impression that the app is super responsive.
Use Suspense and React Query (or TanStack Query)
One of the best ways to optimize API calls in React is by using a data-fetching library like React Query (now called TanStack Query). It provides out-of-the-box caching, deduplication, and prefetching.
With React Query, if multiple components ask for the same data, only one request is sent. Data is cached and reused intelligently. Here’s a basic usage:
const { data, isLoading } = useQuery(['products', category], () =>
fetch(`/api/products?category=${category}`).then(res => res.json())
)
React Query handles:
- Background refetching
- Caching
- Retry on failure
- Pagination
- Deduplication
This means fewer calls, smarter data management, and better perceived speed.
Prefetch Data
Another strategy I often use is prefetching. If I know a user is likely to visit a page or use a certain feature soon, I can start fetching the data in the background before they get there.
With TanStack Query:
queryClient.prefetchQuery(['product', productId], () =>
fetch(`/api/products/${productId}`).then(res => res.json())
)
You can trigger this when the user hovers over a button or starts interacting with a menu, making the transition to the new page feel instant.
Use Concurrent Features in React
React 18 introduced concurrent features that, when combined with Suspense, help make data fetching smoother. While this is still evolving, it enables better control over when and how data is fetched and displayed.
For example, combining React.lazy with data-fetching boundaries can let you load components and data in parallel rather than serially. This is an advanced but promising area for performance.
Minimize Re-Renders During Fetching
Sometimes, slow UI can be a result of too many re-renders caused by state updates during data fetching. To mitigate this:
- Use
useMemooruseCallbackwhere appropriate - Split components to isolate re-rendering
- Avoid unnecessary state updates during loading
This won’t reduce API response time but can significantly speed up rendering after the data arrives.
Use HTTP/2 or GraphQL Batching
If your app relies on many small API calls, consider batching them or switching to GraphQL with query batching. GraphQL lets you fetch all the necessary data in a single request, reducing the round-trip time.
HTTP/2 also allows multiplexing multiple requests over a single connection, which is faster than opening separate TCP connections. These are backend-level improvements but have major impact on frontend performance.
Enable Compression and Caching on the Backend
If you control the API, enable GZIP or Brotli compression. Also, use proper caching headers so the browser or CDN can cache the responses when appropriate. In the frontend, you can take advantage of this by setting Cache-Control headers and storing responses in localStorage or IndexedDB for offline-first apps.
Use a CDN for Public APIs or Assets
For static data like location info, categories, country lists, or other unchanging data, consider using a CDN or caching the response in the browser. If your app calls third-party APIs, see if they support CDN delivery or allow static snapshots to avoid real-time API latency.
Final Thoughts
Improving API performance in a React app is not just about speeding up the server. It’s about being smart on the frontend—avoiding unnecessary requests, using caching and prefetching, optimizing perceived speed with optimistic UI, and taking advantage of tools like React Query. Even if the backend remains unchanged, a well-optimized frontend can dramatically improve user experience and performance.
By implementing these techniques, you don’t just make the API faster—you make your entire app feel faster, smoother, and more enjoyable to use.
