Computer:
AMD Athlon 64 X2 / 4600+ 2.4 GHz
GeForce 7800GTX 256mb PCI-E
2048mb DDR RAM 3200 (2*1024mb)
Tested in a save game of the German campaign mission Battle of Seliger.
Settings:
1280*1024 @ 60Hz
All settings on max
Using 1cpu (confirmed via task mngr):13-17fps(typically 13fps)
Using both cpus: 14-19fps (typically 15fps)
Same settings except no shadows:
1cpu: 15-20fps (typically 18fps)
2cpus: 18-22fps (typically 20fps)
EAX on or off made no differance