Catch-all routes in Next.js are great — until they quietly become expensive.

The catch-all route tax:

One heavy page.
Every page pays.

In the demo for next-slug-splitter, a single heavy page causes every page in the route to ship around ~1250 kB.

After splitting:

light pages: 141 kB
counter page: 266 kB
heavy page: 1250 kB

The heavy page still pays for what it needs.
The light pages no longer pay for what they don’t use.

next-slug-splitter analyzes what each slug actually needs and splits the route accordingly.

No fallback trick.
No runtime magic.
Just analysis-driven route splitting.

This is where it gets really interesting for large e-commerce platforms.

Many commerce setups rely on broad dynamic or catch-all-style routes for products, categories, campaigns, and CMS-driven landing pages.

Convenient structure.
Expensive failure mode.

One heavy page enters the route.
Every visitor can end up paying for it.

A lot of performance work optimizes around the symptoms:

better caching,
image optimization,
compression,
lazy loading,
prefetching,
CDNs,
bundle tuning.

All of that matters.

But sometimes the root cause is simpler:

the route is shipping too much code in the first place.

For high-traffic e-commerce sites, cutting unnecessary JavaScript is not only about a nicer Lighthouse score.

It means less network transfer, faster page loads, better UX on slower devices, and fewer users paying the cost of pages they never visit.

The goal is simple:

Keep the convenience of catch-all routes, without making every page pay for the heaviest one.

Live demo:
https://next-slug-splitter-app-router-multi.vercel.app/

Repo:
https://github.com/project-millipede/next-slug-splitter