Debug slow Next.js operations (NextNodeServer.clientComponentLoading)

[kostas-pblworks]

Summary

Next.js 15.* (App router) app deployed on Vercel (with relatively slow traffic). I'm monitoring using Sentry and I'm observing some slow Nextjs specific operations that I don't know how to debug.

Any one can offer any direction?

Additional information

No response

Example

No response

[priyanshusinghchouhan]

I’ve run into similar traces when monitoring with Sentry. Most of the time NextNodeServer.clientComponentLoading just means the server is waiting to render or hydrate client components. It doesn’t always mean something is broken, but it can highlight slow pages or APIs.

A couple of things you can try:

• Check if you’re doing heavy work inside getServerSideProps or API routes. Those will show up here if they take too long.
• If you’re using large client components, consider moving data fetching to the server and passing smaller props down.
• Enable Next.js profiler locally (NEXT_RUNTIME_PROFILING=1) to see where rendering is slow.
• Also test with next build && next start locally — sometimes Vercel cold starts or edge settings make things look slower than they are.

So basically, use these traces as a signal to look at which routes are slow, then profile those pages or APIs to see if there’s unnecessary blocking work.