I use my PC primarily for gaming. I have a Nvidia 9600 GT overclocked and a E6550 Dual Core Processor overclocked to 3.15 Ghz. A few days ago I was playing Prototype and Resident Evil 5 and they were running around 45 FPS Average. Since then I have downloaded a couple comics and not much else (I mention this because I slightly suspect a virus however I don't think that I have one). What do you think happened to my system in the course of 2 days that made the FPS of these games drop to 29-30 Average.
There is a difference between programs running in the background, and background tasks, backgrounds tasks you will only see via task manager. If something like windows started downloading updates it would have hit your FPS a bit, try to reduce the number of background tasks processes to the bare minimum when gaming to get best performance.
CWillis, when you leave your computer on 24/7 it slows it down alot, computers need to take a rest too, don't leave it on a lot , shut it off regularly, leave it on too much and it keep getting hotter, it will most likely kill your hard drive, trust me, you don't want that, you couldn't play ANY of your games anymore, it happened to my laptop and all I could use was around 6GB of memory. Also clean up some space on your computer, and defrag your hardrive. With stuff spread out all over your hard drive, it takes your PC longer to do things, thus slowing it down, and too much GB used, will also slow your computer down, because usually programs make it to where they startup automatically when your PC starts, so disable some of those programs too.
Jeremey66 shutting down your computer regurly will not make it run faster, restarting it right before gaming is all you need. And keeping it on will not kill your hard drive. If you kept your laptop on your lap then you killed it yourself, you blocked airflow. Computers are designed to be on all the time (desktops). My desktop has been running 24/7 for 2.5 years now and my hard drive works like a spring chicken. Defragging your hard drive won't help either, your Hard drive doesn't even effect your Game performance. Just as i said, the only thing that will help you is maybe reinstalling your OS incase it any kinds of crap filled in it and making sure nothing is running in the background processes that hogs your resources.