You're comparing Sun's Java 7, a mature mainstream, enterprisey language which has probably the compiler, virtual machine and GC most advanced in all of Computer Science's history, with a niche language that some Googlers hacked together. It would be too naive to expect Go to perform better than Java 7. However...
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.