there's a number of benchmarks you can checkout online.

number crunching wise, Go is on par with Java and C#: https://benchmarksgame-team.pages.debian.net/benchmarksgame/...

for webdev work, the standard library might not be that fast, but it's fast enough, and if you need even more speed the fasthttp third party Implementation offers good speed: https://www.techempower.com/benchmarks/