Not just terminals. So much software is unbearably slow today. Definitely terminals. The only terminal I can really stand is xterm with bitmap fonts.

https://danluu.com/term-latency/

> A graphical terminal emulator should use underlying graphical environment features/libraries for things like hardware-assisted rendering.

I've mostly done OpenGL recently, and I think xterm (which is fast) is an exception in that it uses just X11 primitives, but I also know that some font frawing APIs are very slow. GDI is what I have in mind mostly. So using Hardware more directly (i.e. OpenGL) might be not the worst idea.