My MacBook suddenly started running slow
Hello! I've had my MacBook Pro for since 2010 and it suddenly started running slow. This has been going on for a week already. I've restarted my MacBook many times and when I'm not using it I shut it down. I've tried many things to make it run faster and deleted 14k files that were mostly text documents, pictures, videos, etc. and deleted my whole iTunes library hoping it would work but nothing. I currently have 77.07 GB left but space has never been the problem since in the past I've had 10GB or to the point where I had no GB and it still ran perfectly. Two things I've noticed is that when it gets hot it starts running slow and also when I start watching videos on youtube or ones that are already in my MacBook. Last night I reset my SMC hoping it would work better and it only ran slow because of the heat but I see no change. I'm trying anything possible to fix this myself before taking it to the Apple Store and spending money on something I could've probably fixed myself.
Here's some information on my MacBook
MacBook Pro 13-inch, Mid 2010
Processor: 2.4 GHz Intel Core 2 Duo
Graphics: NVIDIA GeForce 220M 256 MB
Software: OS X 10.8.5 (12F45)
MacBook Pro, OS X Mountain Lion (10.8.5)