Screen Lag/Running Slow

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http://askubuntu.com – I am having trouble with Ubuntu 12.10. Everything is working fine, although there is a slight problem. It seems to lag every once in a while, as in I will move the mouse, then about two seconds later the cursor will actually move on the screen. Is there any way to fix this? This is my first day using Ubuntu and I put it on a computer I built myself. I don't have much experience so a detailed answer would be very much appreciated. (HowTos)