I have installed crysis 2 and then played it nearly 3 hours. After I decided to take break and so I shut down the computer. Next day I Booted my system and get to the server for playing game. There I have realized that the FPS dropped from 80-120fps to 5-20. So I have done the clean format of my computer and re-installed the OS as well as the game. It worked well and there was no lagging. Then I installed several apps and programs to my computer. Re-started the system and tried to play again. The game again started lagging. Does anybody know how to fix this?