Dead Rising 2 really bad FPS

[addison]

Specs:
AMD Athlon 2 X4 2.9
4GB DDr2 ram ( 900MHZ)
ATI 5770 XFX edition (not black) OC to 1350mhz and 850mhz
Windows 7 64 Bit (Home edition)
Power Up! 550watt psu.

What is weird is on MW2 I get 90FPS and I heard that's demanding, I play on a 1680 x 1050 and get horrible FPS like 15 when on 1024 x 768 I get 60FPS. I know it's not the PC because I get 90 fps on 1680x 1050 on Black Ops and MW2 with no shadows and 60 with shadows. Is it that Dead Rising 2 was poorly ported for the PC? I have heard this. But my main concern is I know for a fact 15fps is very low for my system, it's pretty decent (yes it's like 2-3 years old) but it should be able to handle this game with 30fps at least. I play Left 4 Dead 2 on max at like 60 fps or even 120fps. I also play PCSX2 with Kingdom Hearts 2 Final Mix and get 60FPS with 3x anti antilising.

I've tried everything I can do with my techincal abalities, still nothing and I'm a regular rank so I wonder is my PC to weak or is it the game of how it was ported.

 

[addison]

Techspot seems to suggest otherwise:
http://www.techspot.com/article/219-cod-modern-warfare-2-gpu-performance/page5.html

it's probably just a bad port, that's what other forums seem to be saying. I assume you've updated all your drivers.

http://www.capcom-europe.com/forum/showthread.php?t=66372
http://www.overclock.net/t/832716/dead-rising-2-horrible-fps-and-stuttering-2x-5770

I'm such a dumbass, when I updated my drivers I now get a amazing 50fps- 115ish with lowest shadows and no AF or MS, thanks you earned the best answer. I will post a youtube vid and include you for fixing this game and making it 100% playable now