This does not have to do w/ retina displays.
I have a 1920x1080 display on a PC (not MAC).
This is basically a fix for high res screens that aren't retina, but for all I know this may fix retina issues as well.
There were a lot of posts all over about blurry or pixilated Ableton displays, mostly text blur issues. I wasn't sure where to to put this solution, so I started a new thread...my first post here.
None of the many threads that I found really helped. A big thanks to PC Audio Labs who sold me my DAW and cured my woes:
1. find the Ableton executable file - which is usually in c:\programdata\ableton\live 9 suite\program\
2. then right click on the .exe
3. select "properties"
4. then under compatibility, tick the box next to "disable display scaling on high DPI settings".
You may have to close and open the Ableton for the changes to take effect.
Not great photos, but on my end its night-and-day wonderful!
before (at 100% in preferences/look-feel/zoom display) - https://drive.google.com/file/d/0B2a9tZ-0i0eLZ3lrUEFRb0x2Y28
[note that although the photo shows the disable box clicked the changes have not been applied in the photo yet]
after (at 120% because everything shrank and I had to increase the display) https://drive.google.com/file/d/0B2a9tZ-0i0eLYXh1RGlxeWVIaGs