Rainbow wheel of doom; computer sluggish overall

Never had an issue with any of the OS X updates until this one. Running on an ’05-’06 MBP and programs take significantly more time to start and load. Will frequently experience the lovely rainbow wheel. It to the point where I need to set aside an extra hour just to get a mobile phone to connect with the computer, only to have the program crash on me again and again.

Throwingapissyfit about OS X El Capitan