Hi. Mine config is rather unusual (2xXeon E5472, 8Gb RAM, GTX280, Win7 x64), and I had very low min_fps values in game, especially in DX10 mode. In hangar on base almost on every map I got 2-3fps maximum, it was real PITA to get into vehicle and go away. I've started investigation on my issues and finally solved them. Now I should publish it.
1. In DX9 mode I have much bigger min_fps value (amost doubled)
2. I've tweaked mine autoexec.cfg and now my min_fps never drops less than 26fps in 1680x1050 VeryHigh.
Here is my autoexec.cfg:
con_restricted=0
r_MotionBlur=0
r_TexturesStreaming=0
r_DisplayInfo=1 // That's for FPS counter in top right corner of screen
d3d9_TripleBuffering=1
r_VSync=1
e_particles_thread=1
e_precache_level=1 // This gives me great boost of performance
gpu_particle_physics=0
r_MultiGPU=0
r_GeomInstancing=1
So, I think if you have FPS troubles, try any combination of this cvars.
works ok for me, even i changed r_MultiGPU=0 to 1

but i still got problems. clearcut is worse... 2gbu's on 11 fps
but i think its crysis.... i just accepted the fact that i have to play on low fps.. even my config is set to medium quality.