Clean Up Your ComputerDefrag your Hard drive every so often, in addition to running a virus scan once a week.
Run Ccleaner and it's registry cleaner for registry errors - as they can make the computer run slower.
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Run Ccleaner and it's registry cleaner (Standard Edition is Free)
-- This helps clean up temporary files, internet cache files and other files that are left behind that are no longer being used.
https://www.piriform.com/ccleaner/download -- PC
https://www.piriform.com/ccleaner-mac -- Mac
How to use CCleaner to fix PC issues
http://www.wikihow.com/Use-CCleanerNote: This post has been locked as it's for informational purposes.