Hmm, I’m wondering if your issue @acrighton is related to a similar sounding issue I’m seeing with the Mac version and v6, but not v5, on a Mac Pro with AMD cards and 4k display? (see thread below) Issue is not present on a 5k iMac with Nvidia graphics, btw.
On your system, in wireframe mode, is there a difference in sharpness between pure wires, and the wire edges of surfaces?