Try checking your hard drive for errors with Scandisk, and also have a look at whether it needs defragging. Looking at the stats of your machine you may have a problem unrelated to FPSC.
Also have a look at any Spyware/Adware that you may have picked up...as well as viruses.
Adaware and Spybot Search and Destroy are both free to download and use, and Webroot do a 30 day free trial for Spy Sweeper which I've found is the best of the lot. If you have a legit version of Windows Microsoft have a good anti-spyware for free download too.
You may also have anti-spyware tools with your anti-virus too, worth taking a look.
Good map design will also help in cutting down loading times, have a look at the manual for tips, especially about not having big open spaces. I've a multiplayer in the Showcase thread that has gone down a storm amongst friends and a couple of them are running it on low spec machines without too many problems.
Hope that helps
Duncan Edwards is the one person who, even today, I really felt inferior to. I've never known anybody so gifted and strong and powerful with the presence that he had - Sir Bobby Charlton