Better stats than time using Linux perf utility. Looks like if you can exclude Java's startup time they are all pretty much very competitive. Clang SVN wins and Go 1.1 native build beats gccgo-4.8. Hmm.
* java version "1.7.0_17" - 485,284,671 cycles, 0.133074106 (0.0577s excl. startup) seconds time elapsed, 3.64% of all branches missed
* clang svn -O2 - 49,227,286 cycles, 0.029045632 seconds time elapsed, 6.70% of all branches missed
* gcc-4.8 -O2 -flto - 56,989,391 cycles, 0.029750578 seconds time elapsed, 6.48% of all branches missed
* gccgo-4.8 -O2 -flto - 114,583,934 cycles, 0.061428897 seconds time elapsed, 2.96% of all branches missed
* Go 1.1 Beta - 109,278,081 cycles, 0.048572937 seconds time elapsed, 2.62% of all branches missed
-O2 seems to be the most commonly used optimization level. That's what most of the distro software and the kernel etc uses. In the past except for maybe a handful things, O3 was an overkill. (O3/Ofast remind me of my Gentoo days! :)
* java version "1.7.0_17" - 485,284,671 cycles, 0.133074106 (0.0577s excl. startup) seconds time elapsed, 3.64% of all branches missed
* clang svn -O2 - 49,227,286 cycles, 0.029045632 seconds time elapsed, 6.70% of all branches missed
* gcc-4.8 -O2 -flto - 56,989,391 cycles, 0.029750578 seconds time elapsed, 6.48% of all branches missed
* gccgo-4.8 -O2 -flto - 114,583,934 cycles, 0.061428897 seconds time elapsed, 2.96% of all branches missed
* Go 1.1 Beta - 109,278,081 cycles, 0.048572937 seconds time elapsed, 2.62% of all branches missed