Mac book pro is very slow I have a mac book pro late 2011.

It has a very powerful hardware. But it is very slow. For example when I'm making expose geisture, there appears 'loading circle' and mac lags for 4~5 seconds. Same as I'm trying to switch to Safari or other program. I can't even sometimes type text normally while I'm having skype call.

How can I diagnose my computer ? Is there common workarounds to optimize performance?
The things to look for first are:


Cluttered desktop
Less then 10% of free HD space
Not enough RAM


Here is a list of 17 reasons why a Mac could be slow. 

When you take a look at it, I'm sure one of them is causing this slow speed problem on your Mac. In my case I caught five similar violations. :)