I have recently migrated a Fortran/C++ application from 32- to the 64-bit compiler. Finally I got a chance to compare performance between the two versions and I haven't seen any performance gains from this migration. The test was performed on two identical machines (Intel 64 bit processors); one runningWindows XP 64-bit and the other Windows XP 32-bit. Compiler settings are the same for both versions. I expected the machine running 64-bit Native code would out perform the one running 32-bit code, but apparently that's not the case.
Are there any compiler settings that are unique to the 64-bit processor that might improve performance of the 64-bit code? Other suggestions are also welcomed.