Biggest issue for me is Twitch, HBO Now, and to a lesser extent YouTube although I've noticed issues with any site streaming video. Even on a gigabit connection and a new $2k desktop, Firefox buffers or the video just goes black and I have to refresh the page to watch for another 10-15 minutes before it happens again. Chrome never does this. I can't be the only person that's had this experience.

I know I also had issues with JavaScript on some sites causing tabs to freeze that wasn't an issue in Chrome as well, but it's been long enough (6+ months) I have no idea what those sites even are now.