I was trying to figure out how Emacs renders so fast in the terminal, especially since I think it might have to redraw a large portion (or all the terminal) most of the time. But I haven't yet dug into the code, but I did compile v25 from source. If there's something specific to look for in the code I'd appreciate the pointer.
Does emacs use ncurses to render in the terminal? (If not, what does it use?)