My laptop's running faster than it should be. Why?

[MrWeavile]

Ok, so i got my laptop about 2 years ago. It was fine up until about 6 months ago. It started to overheat every now and then. Then it got worse, and right now it's overheating every 4 hours. What i don't understand is this:
The only thing I'm running which doesn't NEED to be running is Opera. And my PC fans are running at maximum speed. Also it says my CPU usage is about 50%. Why is my PC doing this?
All help appreciated

[flagstar]

It overheat because of dust cluttering inside your laptop. No questions about it. If you've used that laptop for almost 2 years, more the reason it was dust problem.

If you are not familiar with the component inside your laptop, just send it to near local store and let them clean it up for you.