Be sure to run your antivirus and spyware programs. Also check what processes you have running that could possibly be eating resources. Check it when you don't have anything open and it's been idle for a few minutes, and keep it open and check it when you do things like open Rpgmaker and stuff that normally lags your comp. Also what kind of Video card do you have?

If you haven't run your Antivirus, run it. And if you don't have any (  ) I suggest downloading AVG Free and Spybot Search and Destroy. Avg for viruses, Spybot for spyware. Links for both can be found in the Open Source sticky topic. Be sure all your drivers are up to date, your antivirus/spyware destroyer are up to date, and your Windows Updates are up to date. I can't really think of much more to add other than throw out some maybes. Like maybe your ram got fried or something? You could always google "slow computer" or "computer slowed down" etc., if these suggestions and or other members suggestions don't help.