why your nextjs middleware is so damn slow - By Sourav Mishra (@souravvmishra)

okeyy, so next.js changed middleware.ts to proxy.ts. the name changed, but folks are still making the same mistakes.

i've seen a hell lot of things kill performance, so let's look at the worst ones.

the edge is lightweight

your proxy runs on the edge. that means:

1. no node.js APIs: you can't use fs or regular node stuff.
2. super fast: it has to be quick.
3. runs on everything: it intercepts every single request by default.

mistake 1: db calls

❌ don't do this: connecting to a database in proxy.ts.

// proxy.ts
import { db } from './lib/db'; // ⚠️ big nope

export async function proxy(req) { 
  const user = await db.user.find(req.cookies.get('session'));
  if (!user) return Response.redirect('/login');
}

why is this so bad?

because opening a db connection adds 200ms+ to every single request. we once fixed a client's site just by removing one db call here—bam, 600ms dropped to 120ms.

✅ do this instead: use simple jwt auth or fast redis calls via http.

mistake 2: forgetting matchers

❌ don't do this: running proxy on images and styles.

// middleware.ts
// oops, no config exported

if you do this, your proxy runs for every css file and image. lol.

✅ do this instead: filter that stuff out.

export const config = {
  matcher: ['/((?!api|_next/static|_next/image|favicon.ico).*)'],
};

mistake 3: waiting for geo data

don't waste time looking up IPs from a 3rd party API. just use the geo object next.js gives you.

// proxy.ts
export function proxy(req) {
  const country = req.geo?.country || 'US';
  // fast logic here
}

what to remember

• rename it: use proxy.ts now.
• keep it dumb: only use it for routing and basic auth checks.
• fetch later: do real data fetching in layout.tsx or server components.
• use matchers: skip static assets.

if you're pulling your hair out over css, check out how to fix prod css.

written by sourav mishra, just trying to make the web faster.