Check to see what programs are currently running when you start your PC. Chances are, you have unwanted programs starting and is running without you even knowing it.
To check to see what's running follow these directions.
1.) Start menu, type in run.
2.) Press Enter.
*Run prompt will appear*
3.) Type in msconfig.
*System Configuration propt will appear*
4.) Select the Startup Tab.
5.) Uncheck any unwanted programs you would wish to not start up.
6.) Once finished, click Apply, and OK.
***Your system must restart to make the nessecary changes.***
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All these programs should not affect your PC's personal files it uses to run. It will NOT harm your computer.
This is a very simple easy fix for most performance issues. If that doesn't help a little, let me know. I have other things you can try.