External Display and Blurry Fonts on El Capitan I am one of the many who have extremely blurry fonts on external displays connected to my 2014 MacBook Pro. The solution for me has always been to follow this guide which runs a ruby script and puts the result in an overrides folder.

EDIT: By turning off the new "rootless" feature of El Capitan I was able to gain access to the overrides folder, however it does not appear to have worked. Anyone had any luck fixing the blurry fonts on external displays for El Capitan?
The location of the Overrides directory changed to /System/Library/Displays/Contents/Resources/Overrides/. Note that you will need to disable System Integrity Protection to add files there.