Edit: the Control Panel has a Cleartype wizard that works like an optometrist exam: https://www.tenforums.com/tutorials/80598-turn-off-cleartype...
Which is a great thing, btw! because it helps with all that nonsense-designers-bs of suuuuper thin fonts nobody can actually read.
* "retina" Macs at 16" and 27"
* Windows laptop at 13"-ish and 3000x2000
* Mac and Windows at 24" and 1920x1200
All of these look fine to me, except for Windows at 1920x1200. I don't know if Firefox is especially bad, but that's my primary browser.
I wish I could better articulate what's wrong with it, but I don't think it's fixable with the ClearType tuner. It may just come down to preference--I use Macs more, so I prefer their font rendering.
This is the frustration. Quite simply, I don't think anyone at Mozilla uses Windows.
I've tried to go to Firefox from Chromium, but the psychological impact that font rendering has on me is too much. I mean, we spend a lot of time reading text in a browser. I want that to be delightful and easy on the eyes.