I like Go, but it's not dramatically faster than Java. Any contest between the two of them will probably just be a back and forth of optimizations. They share pretty much the same upper bound.
Also, try running multiple java processes on a machine as opposed to multiple go programs.
No GC I know is happy without a heap several times larger than the program's requirements.
OTOH, Java programs tend to be built using frameworks that soak up memory like crazy. So there's that.