I feel like in a thread like this, Asana deserves a shout-out for utterly fucking up the UX in any firefox version I've tried, up to and including nightly.
Typing in the various text input fields has ~1s of lag. It's a TEXT FIELD for fuck's sake!
Since a few years ago ruining text fields seems to be a rite of passage for front-end developers. I echo the Asana issue and I also noticed Slab (some kind of Notion alternative) both managed to make text lag.
Asana uses ProseMirror and Slab uses QuillJS, and neither of them lag by default if you look at the standalone libraries.. so :shrug:
If you have free time, I'd pop open Chrome Dev Tools, run a performance monitor on both and try to diff out what each of those products do that cause the additional input lag (if there's no code obfuscation).
If you were writing pure JS you'd probably need to intentionally delay text entry with setTimeout/etc to achieve this effect - I don't think you can achieve this outcome by accident.
The problem is that the front-end ecosystem encourages pulling in megabytes of third-party crap for every little thing (including poorly reinventing existing browser functionality) and the result is that some interaction between all that mess causes an entire page redraw upon every keystroke or similar.
To be fair to authors of those third-party libraries, some of the blame has to do with browser quirks, and for a rich text editor, bugs in the implementation of content-editable that have to be normalized across all browsers (unless you pull the engineering-heavy route of rewriting everything in canvas).
Typing in the various text input fields has ~1s of lag. It's a TEXT FIELD for fuck's sake!