Why is a better platform more slowly than an old one?

[hushujun]

My new platform is :

Pentium D 820 +Intel 845PSN +WinXP 64-bit version 2003+ Intel fortran compiler with EM64T. But the compiled program (small, only 3**k)from it performs more poorly than the old one as:

Pentium 3.0E + WinXP 32-bit + Intel fortran compiler (32-bit).

I donnt know why. Maybe there islack ofsome optimization parameters.

It is pleasure that any one gives a explaination or suggestion.

[Steven_L_Intel1]

The Pentium D 820 is dual-core, but each core runs at 2.8GHz, compared to the 3.0GHz of your other system. If you can take advantage of the dual core by use of OpenMP or autoparallelization, you may see an improvement.

[hushujun]

Thanks for your reply. I am sorry Idid not described the problem correctly. I means that the running time oftheprogram fromthe newplatform almost doubles that of the old one. Butfor the new platform with the 32-bit system and compiler, there is no obvious difference. That is the problem.

[Steven_L_Intel1]

Sorry, there's nothing in general I can suggest, unless your new computer has less RAM than the old one and your program uses lots of virtual memory. With the Pentium D, you can set the option to generate code for Pentium 4 with SSE3 Instructions, and you may see an improvement. Do make sure you're building a "Release configuration".