Thanks. Yes, I tried all possible parameters for font rendering in Firefox. For some reason none of them match the sharpness of the IE rendering.
Have you considered using a 4K screen with 200% scaling? That would considerably sharpen text in any situation compared to a 1080p screen.
Yes, but (a) there’s too much software I still use that isn’t hi-DPI capable, and (b) I use a 1920x1200 display so would lose 10% vertical height, which is quite significant.
It’s all a question of trade-offs of course
However while looking around at a bug report to get MacType to work in Firefox [0] I came across a setting in Firefox's about:config [1] that can change the font rendering and that might help you out. Not sure about the history forking thing but there may be some Firefox extension to help with that.
[0] https://github.com/snowie2000/mactype/issues/673 [1] https://bugzilla.mozilla.org/show_bug.cgi?id=652141