Why is it slow?

I got my new 12" PowerBook G4 about 2 weeks ago. It was running well for about a week and a half. Recently, it's been getting a little slow. I have no idea why. Like I would go to the Dock, click on a program, and it would pause then start opening(like I would click, and it wouldn't start bouncing as quickly as it used to). Minimized safari windows wouldn't open as quickly as they used to. I have MacJanitor, but it seems like it's not helping. Is there anything else I should do to help it run faster? I have 256 MB RAM.

If you just got it and you have the time I would wipe the hard drive and start fresh if you didn't when you picked it up... See if that helps.