Many have asked for this, there is even a thread from august on dev that is closed, one would assume is because its finished? https://developer.blender.org/D1619
I just went though all the settings and couldn't find anything. How can I halve the resolution of viewports for 'retina' like displays?
(pls no answers that suggest changing my cycles render settings when previewing etc, that is not what I'm asking about)