13" Macbook Air 2013 on El Capitan 10.11.1 here.
This just blew my mind...Retina DisplayMenu actually allows one to change a resolution on a Macbook Air all the way up to 2560x1600!
Granted, the higher from 1440x900 you go, the blurier things get - 20/20 vision required! - and it's useless for photo/video editing/hardcore reading anyway, but for the odd occasion when I need more desktop real estate for spreadsheets, this trick will neatly bridge me over until the rMB catches up in CPU speed.

This just blew my mind...Retina DisplayMenu actually allows one to change a resolution on a Macbook Air all the way up to 2560x1600!
Granted, the higher from 1440x900 you go, the blurier things get - 20/20 vision required! - and it's useless for photo/video editing/hardcore reading anyway, but for the odd occasion when I need more desktop real estate for spreadsheets, this trick will neatly bridge me over until the rMB catches up in CPU speed.