[rayiner]

The web stack is abysmally slow, so you have to carefully pick the levels at which you offer extensibility. Emacs doesn’t have to worry about a DOM, CSS, etc. There’s just not that much between between grabbing input events, storing a character in a gap buffer, updating a glyph matrix, and painting the screen. And it’s all heavily optimized to be usable over ancient serial links: https://web.mit.edu/~yandros/doc/craft-text-editing/Chapter-.... So even making each of those steps heavily programmable in Elisp—every key press invokes a Lisp function that can be rebound, or adviced-around, still ends up performing reasonably well on a modern machine.