I discovered this by accident. You can use this until Crytek will release a new patch. I checked it in multiplayer, works for me every time. So if you want to increase your FPS, simply go to the match and then run the "task manager". The game minimize. You'll see the desktop. Then close the task manager and go back to the game. Since then Crysis will gain at least 10 FPS. I know it's weak solution, but it's better than nothing. Without it, I can not even play. Patch 1.9 terribly broken optimization. Let me know if it also helped you, or if you found a better solution.

In-game go to options > graphics and turn v sync on then turn it off, applying the changes both times of course, it's cause it lowers your monitors refresh rate, turns my 60MHz to 50MHz, i gotta do this fix every time i load the game up, and yeah it sure does need optimized, fu-ckers nvidia holding off with their drivers till everyone updates equipment.

I do not think it had something to do with drivers, because in previous patches were not problems like these.

I stumbled upon OP's fix too.

In MP, my vram jumps to 90% full (Dx9 everything OFF) at the beginning of a match (right when the sound effects start on the "wireframe buildings" screen). Soon, stuttering begins.

Using OP's technique, vram usage drops by 225 to 300+ mb (!) and stuttering goes away. Vram usage will steadily climb during the match, sometimes requiring a second application of this trick, which always works. Skyline has its own set of issues...

This technique has no great effect on vram in DX11 SP. Haven't tested in DX11 MP.

(2x460 w/768, 275.xx drivers)

SIDE NOTE: I'm getting great results with SP DX11 all maxed + textures using D3DOverrider v2.01 (which forces vsync and working triple buffering) with in-game vsync off. Smooth gameplay so far. Very nice fix.