I know I'm getting a new computer soon (I'm trying to wait as long as possible before Aion comes out, so I can get the best possible, but its hard

), but playing L2 in mass PvP I'm getting like 5-10 FPS, however in other non-populated area I'm getting about 40-60 FPS on max settings.
The weird thing is putting it on lower resolution (1024x768) and low settings does not increase my frame rate at all...I'm wondering why that is, maybe its my CPU?
I've got an AMD 4000X2 2.4GHZ S939
2GB PC3200 DDR
Geforce 7600GT PCI-E
750 GB Seagate Caviar
XP Media SP2