Serious Apple computer problems...?

I have had my macbook for around 3 months and it has been working fine until a few days ago. It's very slow now. It takes Safari 2 or 3 mins to start, that stupid compass jumps up and down over 100 times before anything happens. I can't watch Netflix anymore, it keeps telling me i'm having "Plug-in Failure." First I thought I had too much crap on my computer so I deleted a bunch of files and even some apps. That did nothing. I have MacCleaner and i have scan the computer a bunch and it says nothing's wrong. So I updated my flash player and Silverlight and that did nothing. It's so bad I can't type more than a few words without it freezing up and that colorful pinwheel popping up. Can someone tell me what they think may be wrong and how to fix it?