FPS Problem?

[wiregrind]

The "Maximum" settings on PC disable options like occlusion culling, in theory it would make the game "better" but in practice it might be what's killing your framerate (with almost no visual improvement).
Try playing on the "High-Desktop" settings and see if the FPS are more stable.

[Lacard]

Yea try turning things off that may lower performance. Also, download HWMonitor and while the games running, look at your maximum degrees of various components. What I did is put the game in windowed mode so i can watch both at the same time and found out that when mine got to a certain temperature, it would throttle and FPS would drop to 10. So I knew I was overheating. A good cleaning may be what you need. I took apart my heatsink and cleaned it real good.