I'm not so sure; people keep adding stuff to emacs, and performance doesn't really seem to be a priority. To give a couple examples off the top of my head:

- A recent version of emacs changed the default shell history command to show live search results (like bash does), but the emacs implementation was ungodly slow if your bash history was longer than a few dozen items (waaay slower than a real terminal interactive bash search). Moreover, it completely locked up emacs while doing the search (since emacs is single-threaded and synchronous). After the suffering got high enough, I finally tracked down how to revert to the old behavior.

- The latest emacs python mode for some unknown reason would freeze for like 10 seconds when opening certain python files. Rather than track it down, I went back to using the latest python-people python mode (for some reason, the emacs people insist on writing their own python mode, rather than using the one the python people wrote). The python-people python mode doesn't lock up, but narrow-to-defun takes maybe 300ms (not terrible, but clunky feeling; way worse than instant), for some reason.

- Or check out this awesome, high-performance code from the function comint-exec:

        ;; Feed it the startfile.
      (cond (startfile
	     ;;This is guaranteed to wait long enough
	     ;;but has bad results if the comint does not prompt at all
	     ;;	     (while (= size (buffer-size))
	     ;;	       (sleep-for 1))
	     ;;I hope 1 second is enough!
	     (sleep-for 1)
	     (goto-char (point-max))
	     (insert-file-contents startfile)

See that sleep-for? That's an awesome built 1-second pause while waiting, for example, for an emacs shell to startup if you have a custom .emacs_bash defined.

There's lots more stuff like this. Emacs is a giant ball of elisp mud that's perpetually half-broken, half-implemented, or slow...but it's still the best thing going, by more flexible and more useful than any other editor out there (AFAIK).

But I'm not convinced it isn't possible to do something as flexible as emacs without all the random breakage and general lack of concern for performance. Think maybe replace elisp with LuaJIT, and take cultural inspiration from the make-it-fast ethos of git and the make-it-correct ethos of sqlite. Something like that.

Oh, and also, unlike every modern day attempt at an editor, it should still support running in a terminal, because terminals are still damn useful.

So yeah, could someone get on that please? Thanks :)