There are some mistake in your reasons of performance increase. (I'm work in computational optimitation and i'm a newbie boys of gcc@...) tree-ssa will be avaible only from gcc 4.0 (next major) the flag -msse or -msse2 can or cannot increase your performance, but they don't activate vectoritation, they only ask to the compiler to use simd instruction (see gcc's info) you can yous -mfpmath=sse,387 (as from gcc's info). 30% it's a good result, but how do you obtain this number? (old perl version, old flags, old compilers flag etc.) Recompiling can however increase your performance (Slack + Gentoo rules ;)) P.S. The intel C compiler works fine in vectoritation but: 1) No source code 2) No good code for Non-Intel 3) No AMD64 support