Does your Mac constantly hang with the beachball of death when doing file tasks such as saving and opening files? Then the following may be your solution.
It seems that if you add any external drives to your favourites list and then remove those drives from the Mac it still goes looking for them as accessible drives for file operations, this may result in a constant file hang delay that can last 30 seconds plus every time.
This may also have an impact when using applications that either access drives during operation such as DAWs or those that make auto-saves.
To stop this happening simply remove any drives that are no longer attached to your Mac from the list of favourites. This seems to be the case on numerous versions of Mac OS X, including Mountain Lion and Yosemite.