I, for one, found that for some kinds of work I do, Go doesn't give that much of a performance advantage, so I'm exploring other languages.
That said, even if Java gives you 2x, that doesn't mean that you shouldn't complain about Go.
E.g you might like Go's semantics and syntax, or it might have other benefits for you. That you like those things about Go, doesn't mean you don't get to say "shame about the performance".
a) writing in C for performance (and having to setup glib et al to make it comfortable)
and:
b) carrying the JVM with me to run something.
(And, no, I won't consider AOT compilers for Java. I want to deal with reasonably mature and widespread technologies and tooling).
So, there are my constraints. Given those, maybe C++ is the ticket. D is not mainstream enough, and Rust I've played with and I like very much but is still in flux.
Let's be specific. What are you building or considering, where your current options are C and the JVM? How does Go fall down on that work load?
I've got a fair bit of professional experience in both C (~10 years shipping code continuously in it) and Java, and I've spent the last couple weeks in Go --- not long enough to be a true believer, but enough to have some practical experience.