core-ai-bot
commented
3 years ago 
It's not clear that there's much we can do about this, short of trying to roll a new version of SourceCodePro with different hinting. There's no way in CSS to turn off subpixel positioning (fractional char sizes) without also turning off subpixel AA -- even though at the OS level they can definitely be controlled independently. (For more on the Chromium side, see this comment and this possibly related bug).
OTOH, native code editors all seem to consistently disable subpixel positioning (while keeping subpixel AA) -- Sublime, Visual Studio, Notepad++, and even Notepad do this. It's a bummer that we can't, but it may well be a fact of life for now.
In the new CEF, text seen in the editor is spaced noticeably farther apart:
It's subtle -- 39 chars in new CEF take up the same space as 40 chars in the old one -- but it definitely jumps out at me in the overall visual impression every time I switch between the builds.
That might beg the question how a fixed-width font can change size by an increment that's not a multiple of the number of characters (i.e. increase every char's width by 1px, or none of them). The answer is that glyphs are now fractional width in the new CEF:
Notice how in the first image (1547), the subpixel AA looks the same for every copy of the character. But in the second image (2171), the AA gradually "shifts phase" in a cycle of 5 chars -- so over the course of 5 chars, the char shifts over one full pixel.
In other words: in the old CEF chars were exactly 7px wide; in the new CEF, they're 7.2px wide.