Download Driver Booster. Let it update everything you need. http://www.iobit.com/driver-booster.php
Also get Jet Clean. Let it fix any registry issues that you might have. http://www.bluesprig.com/jetclean.html
I wonder if you have some sort of malware that is chewing up your CPU cycles.
Update all of your anti-virus software and run a full scan.
If you want to be extra careful, download a program such a CCleaner and use the option to write all zeros to the nominally 'unused' space on your storage drives to kill any hidden malware. That takes a long time, so it's probably something you would do overnight while you sleep.
I don't want to go into too much detail about software on a forum that's dedicated mostly to hardware, but there are some easy things that you can do to clean up the system.
I recommend that you download JetClean and run it. I have an old laptop that get its memory clogged up from programs that don't deallocate the reserved memory areas when they are terminated. Use the "RAM Clean" option just before you start the game to clean up the memory.
Yeah, thanks, I especially liked the BES (http://mion.faireal.net/BES/), and will certainly give JetClean a try (http://www.bluesprig.com/jetclean.html), although I'm not sure it's much different than CCleaner.