First you need to properly uninstall MacKeeper crapware off your machine.
This guy is keeping on top of their B.S. tactics and knows how to REALLY get it off.
http://applehelpwriter.com/2011/09/21/how-to-uninstall-mackeeper-malware/
My question remains, how can I learn to do the clearing of junk that slows the computer?
First you have to understand how your computer works and what can slow it down, corrupted caches are just one facet of the overall performance issue.
Why is my computer slow?
I do have a free OnyX cache cleaning routine here at #6, and if there are corrupted caches then doing the OnyX will rebuild them anew and cure the corruption.
However if you haven't tuned up your Mac before, you might need to do more Steps as needed.
.Step by Step to fix your Mac
Backup as always
Most commonly used backup methods
If you want a free evaluation from others online to assist further, then do this and report here the results.
Tune up your Mac here
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