My friend's MacBook Pro (2011 15", 2GHz i7 running OS X 10.9.4) is incredibly, ridiculously slow. I'd be interested to know how to improve it. Some examples: Start-up takes several minutes. Clicking on the Apple logo gives a spinning wheel for about 4-5 seconds before the menu appears. Then clicking 'About this Mac' gives the spinning wheel again and it takes about 20 seconds to open the About this Mac window. Opening Mail takes around 4 minutes. The whole thing is generally very, very slow. Any advice?!