Fixing Client-Server Waterfalls After Migrating from Vite to Next.js

The Post-Migration Performance Paradox

You’ve done it. You moved your React application from Vite to Next.js to take advantage of Server Components, better SEO, and optimized routing. But when you open the Network tab in Chrome, you see a familiar, frustrating sight: a staggered staircase of requests.

Even after switching to a framework designed for the server, you might still be suffering from Client-Server Waterfalls. This happens when your application waits for one network request to finish before it even knows it needs to start the next one.

In this guide, we will dive into why waterfalls persist after a migration and how to refactor your data fetching to truly leverage the Next.js App Router architecture.

Why Waterfalls Happen in Vite (and Stay in Next.js)

In a standard Vite-based Single Page Application (SPA), data fetching typically lives inside useEffect hooks or libraries like TanStack Query.

• 
  Component A mounts, triggers fetchUser.


• 
  Component A finishes loading, renders Component B.


• 
  Component B then triggers fetchOrders.

This is a classic waterfall. When you migrate this code directly into Next.js Client Components ('use client'), the behavior remains the same. You are still shipping a large JavaScript bundle that must execute on the browser before the first byte of data is even requested.

Step 1: Moving Data to the Server

The most immediate fix is moving your fetch logic from useEffect into an async Server Component. By fetching data on the server, you move the waterfall closer to your data source (database or API), which usually results in significantly lower latency than a round-trip from a mobile browser.

// Before: Client Component (Vite style)

'use client'

function Dashboard() {

  const [data, setData] = useState(null);

  useEffect(() => {

    fetch('/api/stats').then(res => res.json()).then(setData);

  }, []);



  if (!data) return <Skeleton />;

  return <Stats display={data} />;

}



// After: Server Component (Next.js style)

async function Dashboard() {

  const res = await fetch('https://api.example.com/stats');

  const data = await res.json();



  return <Stats display={data} />;

}

Step 2: Avoiding Sequential Await

A common mistake during migration is turning a client-side waterfall into a server-side waterfall. If you have multiple independent data requirements, don't await them one by one.

// ❌ Slow: Sequential

const user = await getUser();

const posts = await getPosts(); // Doesn't start until getUser finishes



// ✅ Fast: Parallel

const [user, posts] = await Promise.all([

  getUser(),

  getPosts()

]);

By using Promise.all, you initiate both requests simultaneously. This is particularly important if you used a tool like