I'm currently playing on lowest settings (1080p) at around 40fps average, and half of the maps (Shanghai, Dawnbreaker, Resort, Zavod, and Flood Zone) are basically unplayable with <30fps. For some reason my auto/optimal settings are set at High on all sections.
What bugs me is that I'm getting 85% avg CPU usage and 50% avg GPU load, which doesn't make sense. I'm wondering if it has to do with Vista, which I heard performs poorly with CPU intensive games.
Intel Core 2 Quad Q8200- 2.33GHz
8GB DDR2 ram
MSI GTX 660
So far, I've tried:
1. Checking all drivers (OS, chip, GPU)
2. Driversweeped hard drive.
Like the others said, your CPU is your biggest hold back. Though DDR2 probably is a bit too. The graphics card isn't bad. I'm sure everyone would agree if you can afford it that a CPU, motherboard, and RAM upgrade is your best option.
However if you have access to a super cheap copy of Windows 7, it couldn't hurt. Windows 7 performs a lot better than Windows Vista. It eats up a lot of resources in general, but theres no telling how much that would help. Probably only get 1-2FPS improvement from a lower CPU use. So unless you have a really cheap Windows 7 copy available, or you are getting a license you can use again when you build a new computer its best not to worry about changing OS. However if you do plan an upgrade in the next year or so, you might want to consider it if it can be reused, because you will need it when you build the new computer anyways.