I'm finding that on Macbook Pro running Sierra or Mojave that Firefox 88 'hangs' when there is a lot of emotes in twitch.tv chat, and when I try to type I can watch the text fill in slowly after I've finished typing letter by letter. It doesn't matter if the twitch.tv streamer has 70 viewers or 3,000 viewers, the behavior is the same. I've refreshed, deleted cookies and cache, lowered the quality of the stream to 380p, used the latency slider, etc etc etc and nothing seems to be correcting the problem with chat on any given twitch.tv stream. I have 12.30 GB memory available and it's still an issue.