> "It is not as slow as it sounds."

Yes, it is. 5%-10% in the very link you posted.

> "golang do heavy inline-ing"

No, it does not. See https://github.com/golang/go/issues/17566

> "most of its performance comes from concurrency"

That's just ridiculous. They didn't write all crypto and math in assembly just for nothing. Lumping bunch of slow function calls onto several threads is not where performance magically comes from. And you are confusing concurrency and parallelism.