You chose Next.js for performance, but your app feels sluggish. Loading states everywhere, slow page transitions, and users bouncing before content loads. Here's what's actually causing the problem—and how to fix it.
The 5 Most Common Next.js Performance Killers
1. Client-Side Data Fetching (The #1 Mistake)
The Problem:
```javascript
// ❌ DON'T DO THIS
export default function ProductPage() {
const [product, setProduct] = useState(null);
useEffect(() => {
fetch('/api/product/123').then(res => setProduct(res.json()));
}, []);
if (!product) return ;
return
{product.name};