A couple of questions:
1) How does Go compare to other languages for performance?
2) Is it portable like Java (write once, run anywhere)
3) following on from 3, does it run in it's own JVM like container?
Go compiles to native. It's fast.
In most of the benchmarks, performance and memory usage is better than Java.
http://benchmarksgame.alioth.debian.org/u64q/go.html It's write once, run anywhere, but not compile once, run anywhere. You still have to compile for the target platform, since the compiler generates native code.
The compiler itself is reasonably fast too. Not as good as Java, but then that's to be expected since the Java compiler generates byte codes rather than native.