[newt0311]

Understand that unless the C/C++ code being compiled is actually targeted for gcc optimization, you won't get more than ~2-5% speedup in code even with -O3 or higher. Infact, go high enough like -O9 and you may even get incorrect code. The only time that settings like -O6 help are in cases like XaoS which is targeted for gcc optimization.

Furthermore, MSVC is not the only compiler better than gcc. As of now, LLVM also produces significantly better code: http://news.ycombinator.com/item?id=286408