Definitely looking forward to the final article in the series!
Notice that Go, compiled with the Plan 9 compilers, performs as well as Java in 7 of 11 tests and uses as much as 1/15 of its memory. All in all, not that bad.
From what I can tell, on the Language Shootout, only C, C++ and Fortran beat Java.
N.B. I think I only looked at benchmarks for x64 quad core.
Here are the results on a x64 quad: http://benchmarksgame.alioth.debian.org/u64q/benchmark.php?t...
Overall Go loses here aswell, but it does much better than in the comparison you linked, and like others have mentioned Go is still very young compared to Java.
Also, glancing at the tests where Go does really bad against Java they seem to be tests which rely much on runtime functionality, and the Java runtime/VM has had a very long time (+10 years?) in which to improve to it's current state.
As for code performance, GccGo atleast seems to have the upper hand in code which doesn't rely much on the runtime functionality, but not by very much on the (admittedly few) tests I've done compared to the Go 1.1 6g compiler.
That said, AFAIK GccGo doesn't yet have the improvements made to the Go runtime in 1.1, so chances are it will beat the Go 1.1 6g compiler even in runtime reliant code once those improvements make it into GccGo.
Even so, the official 'plan9-derived' compilers have been improving greatly during their relatively short existance, and as they are the main target of optimizations/improvement aswell as being 'Go specific' they will likely end up generating faster code for Go in all scenarios.
I see GccGo mainly as a solution for platforms to which Go hasn't yet been ported (or perhaps never will), and I think it will remain as such. The main focus, and practically all the end usage will be on that of the official compiler suite.
It will be interesting to see how much more performance they can squeeze out of Go compiler optimization, GccGo has proven that there is more to be had.
I would also like to see profile guided optimization on the Go compilers, I've had cpu intensive code where GCC has given me 10%-20% better performance on PGO builds (this was not Go code, I don't know if GccGo supports PGO?).