I had just upgraded my website to next.js 16. In development it all worked well and ran smoothly. However, once i deployed the new version, i noticed that performance of my website went down drastically. Loading between pages would often completely hang (showing my loading spinner indefinitely, until i decided to F5 which would bring me to the page immediately, for some reason). Sometimes clicking on internal links just simply wouldnt start any routing and nothing happened. Opening links in a new tab worked and the page basically loaded instantly too. I traced the server logs and saw no errors or issues, and building and testing the app on my local machine also didnt produce any of these issues.

Im using Material UI (which only supported next.js 16 with legacy-peer-deps) and also cloudflare as a CDN in case that is pertinent to my issue. I have now fixed the issue by reverting back to next.js 15.4.8 and everything is back to normal and running well.

Does anybody have an idea what could have been the cause for the issues i experienced, in case i do want to upgrade to next.js 16 in the future again?