As someone who has dabbled in terminal emulation (I was the maintainer of Console Telnet for Win32 twenty years ago), I have respect for someone who takes the time to optimize a terminal emulator by building a fast parser and being careful with screen updates.

That used to be the only way to make a graphical program fast, but these days hardware is so fast you can render an entire scene before the next screen refresh and still have cycles to spare. As long as you initiate rendering early enough, it's hard to go much faster.

I'm curious how foot compares to older fast terminal emulators such as Eterm, xterm, and rxvt. I think libvte is neat (anyone can write a terminal app now) but is it resulted in terribly slow programs like gnome terminal. Before that terminal emulators tended to be much faster -- they had to be, because hardware was so much more limited.