How much traffic could they possibly have? Quite frankly either gitea has absolutely terrible scalability or something else is off here.
Edit: i misread the parent comment. My bad.
Edit: i misread the parent comment. My bad.
Gitea performs alright. It can serve surprisingly-heavy traffic from a potato-tier VM with a SQLite backend (assuming the host network can keep up with it, anyway). Not Github-scale (but Github has... a lot of traffic, including a whole lot of write traffic) but quite a bit, and that's with basically the worst-possible hosting situation for handling high load.
Disclaimer: I'm one of the members of the technical oversight committee of the Gitea project, and am employed to work on Gitea.