My FF+UBO has some minor hicups like sometimes I need to refresh to get the video to play as it just sits on a black screen (dark mode) with a spinning circle, that is my only issue and usually only once every few days. Oddly enough on Chrome (I use different browsers for different tasks) yesterday when I tried to start a stream the page refused to load, when it mostly did 2 panels would not load, when I went to reuse settings from a previous stream the entire page was missing all the info, after a reboot and 10 mins it finally worked.

Edit: For some reason I did not think to check my cpu usage so can't say if I was at 100% or what