I have 2 systems I test and use FPSCreator on here.
Programming Rig: (I use this daily)
AthlonXP 2600+
512MB PC2700
GeForce FX 5200 64MB AGP 8x
Windows XP Service Pack 2
DirectX 9.0c
IBM 120GB ATA-100
Gaming/Testing Rig:
Athlon64 X2 4200
3GB (3x 1024MB) Hyper-X PC5300 ECC
GeForce 7800 GTX 256MB PCI-E
Windows Vista Beta 1
DirectX 9.0L
Raid[0]IBM 300GB SATA-150
Raid[1]IBM 300GB SATA-150
Raid[2]Western Digital 250GB SATA-150
Can't say I've had any problems except for entities after installing FPSC. Did an UnInstall Delete and things were fine again.
I can run both computer with the same map and expect identical results with full graphics. Going in to debug mode and pressing 'x' tells a different story.
WW2 for example will run at around 90FPS on my Programming Rig, where-as on my Performance Rig I get ~3,500FPS
Ridiculous how much performance has been gained over the past 3years. The problem with speed is purely down to how the engine is programmed. Nothing else, and this is going to changed over the next few months.