Everything, including zed, looks fine in the 95dpi (1080p 23") monitor I use right now with my macbook.
I have had similar blurring problems with a certain monitor (1920x1200 27"), which was resolved with changing some sharpening settings in the monitor itself. Strangely, that setting did not look well at my colleague's macbook, who was also often using that monitor, while the original settings looked fine, so we had to change the settings back and forth every time the other person had to use it. I do not think I was using zed at the time, other apps had that issue.
