caddy is written in terms of net/http, nginx is written right on top of epoll/kqueue with bespoke HTTP/1x parser in a manually memory managed language. I think the point was not that go is "faster" than anything, it's that it makes it easy to write hard-to-beat network software once you get out of the realm of toy or highly specialized problems.
Maybe a highly tuned nginx by a Russian neckbeard. Who ridiculed you for ever attempting to use nginx without first consulting with an archaic text.
Otherwise nginx is a piece of garbage web-server that likes to pretend it’s 1995. On top of that, it’s one of the most inhospitable toxic communities I’ve ever encountered.