My Computer:
i5 750 at stock 2.66ghz
EVGA Nvidia GTX 460 stock clock
Seagate Momentus XT + Intel X25 40GB SSD
Gigabyte Mini-itx GA-h55n-usb3 Motherboard
Silverstone SFX - 450 Watt Power supply

My game runs amazing when I reinstall it! After I've played it for a few days with breaks in between, I start the game and the videos are choppy and the game is running at half FPS. I have looked all over the internet but have not found why it is going so slow. Is there some cache I have to clear? There is no processes im running that will hinder its performance. It must be something!... perhaps the power supply cant take it?
Is anyone having this problem?

My computer eats through everything I throw at it until now...

Defrag?

I first installed it on my SSD but it was the same situation. I will defrag my Momentus xt to see if there is any difference but I did not think it was the drives.

use an on-screen FPS monitor like 'MSI AfterBurner' has, once the game is started set the v-sync to on or if you got it on set it to off, now set it the other way and your FPS should jump up, you using HDMI?
Maybe it's your card that needs a 0.05 voltage boost too.

I am using HDMI as a matter of fact. I have not touched the voltage on my card but I am not afraid to as I over-clocked parts before. what would the hdmi do?

Crysis 2 through a HDMI l,ocks your monitor @ 50Mhz, do the v sync trick, this problem has been described as 'the v sync bug', try the fix and monitor your FPS to see them jump you need to do this every time you start the game up.