My computer has been really slow for about three months?

There are lots of little things that slow down a computer, mostly it is programs that are running, but day to day clutter can slow your computer down too.

A good thing to try is to download a good program like Ccleaner or Reginout. I personally Use Reginout because i don't believe on free products.

It will analyze your computer, and clean up all that it can safely clean, inducing your registry.

It works well, and is 100% reliable.

if your pc slowdown check the the heat sink grease if its dried up. your pc slow down as it mean to say its overheating. no program can repair it.

replace your heat sink grease. i recommend arttic silver 5

check the background program running in your computer.you can see on the right side bottom of your screen.that is cause also to slowdown your computer.to disable all of that

click start button on the left side of your screen and then write MSCONFIG and then theres a small screen come out click STARTUP and then on the bottom disable all and restart your computer see if theres any changes.