I agree that I've never had a problem with terminal speeds on Linux. If you're using urxvt, that's probably going to do just fine.
Where I have had problems has been on the Mac, where the system default "Terminal.app" or popular alternatives like "iTerm2.app" can each be catastrophically slow if you have a lot of control codes (as in, for example, rapidly paging through a large document in vim with an intensive color scheme active), and it could just take noticeable fractions of a second to redraw a fullscreen terminal window.
Moving to a faster terminal emulator like alacritty or kitty did make a good quality of life improvement for me in that specific use case.
Where I have had problems has been on the Mac, where the system default "Terminal.app" or popular alternatives like "iTerm2.app" can each be catastrophically slow if you have a lot of control codes (as in, for example, rapidly paging through a large document in vim with an intensive color scheme active), and it could just take noticeable fractions of a second to redraw a fullscreen terminal window.
Moving to a faster terminal emulator like alacritty or kitty did make a good quality of life improvement for me in that specific use case.