|CCleaner is a good tool for cleaning away junk.|
If you have more than one AV or Anti-Malware product running continuously in the background that can slow things down.
Otherwise you might have a few unnecessary programs running. If you type msconfig in the Run box, hit Enter key, and look at Startup, that will give some clues. Some programs don't really need to run all the time.
There might even be some running programs that can be fully uninstalled.
Please come back and let us know the outcome.