You seem to know a lot about my server. From what I could see, all cores were pinned to 100%, but maybe my budget AMD CPU is hiding fantastical amounts of compute from the kernel. I'd love to know how to make use of it.
I have no idea what the site you linked does, but it doesn't look like a cgit instance to me; that's what got hammered on my end, and when hosting it, one very quickly finds out that many git operations are CPU-bound.
If you want credibility from the get-go, you need to be up front about your application. I certainly took it to be a generic host for an unpopular site in your first comment.
Funny. My site is a search engine and cgit is one of many tarpits that I block. Otherwise the index gets filled with garbage and the crawler hits TCP conn limits because the bytes trickle in too slowly.