Citations please. While I am not necessarily saying I don't believe you (because a properly tuned JVM is lightning fast), making a statement like this without numbers to back it up is a gaping hole in your argument.
http://benchmarksgame.alioth.debian.org/u64q/go.html
Keep in mind this is comparing Go 1.4, I'd expect 1.5 to do better.
http://benchmarksgame.alioth.debian.org/play.html#java
The notable exception (not included in summary measurements) is the few tenths of a second run-time for meteor-contest. Of that few tenths of a second: JVM startup takes 95%, JIT and OSR another 4.9%.
Whatever kind-of app you have, you should take general statements about program performance with a grain of salt, there's even a page for that --
http://benchmarksgame.alioth.debian.org/dont-jump-to-conclus...
https://www.techempower.com/benchmarks/#section=data-r9
And arguably more real world than microbenchmarks.
Here's one example:
// imagine a for-loop around this
s := foo[i:i+4]
s[3], s[2], s[1], s[0] = s[0], s[1], s[2], s[3]
The reasonable assumption is that the second line generates either zero, one, or four bounds checks on s. However, the Go compiler likes to be sure, and turns it into 8 bounds checks.
I agree it's not a typical for a server to spend the majority of it's time swapping bytes. In the rare case that happens, you're going to hate the compiler for not being smarter.
EDIT: fixed formatting of the example
We shouldn't be under-selling how light the Go footprint is. In the long run it may be one of the few languages to compete with unikernels.
Can you please clarify what this means? I don't really understand what it would mean for a language to compete with a unikernel.
This is no surprise considering that go is a compiled language and the java garbage collector has had decades of very smart people working on it.
Let's also not forget that Java is significantly faster, has every library under the sun, has a dependency system that actually makes sense and you have seamless interop between multiple languages e.g. Ruby, Python, Scala, Clojure.
Anyone who thinks Go is an upgrade to Java is woefully misinformed.