Example - my submission 9959592 (problem 1990 - Podracing). It's not about input or sorting (checked everything), but GCC gives 0.5 sec where VC++ gives 0.171 sec (it was 0.9 sec on the verge of time limit when everything was double). FPU is just a guess because I faced situations before in real projects when GCC used FPU and VC++ used SSE or something else and was way faster, there was some command-line switch like -fdisable-fpu or -fdisable-387 or something like that for gcc (can't remember now), probably it will help.