Here is the solution to fix the game lag for people with Saitek keyboards.

Goto your device manager and disable all the USB Input Devices...
http://i34.tinypic.com/5wa61x.jpg

Solved my problem, No more game lag for me.

I'm not having any trouble with my keyboard but for some odd reason there are times when I need to click to target something and the game won't let me move my mouse any great distance on the screen. If I fight with it, change weapons back and forth then it usually sorts itself out but it has nearly cost me a few multiplayers.