I'm not convinced that Elisp-the-language is really the limiting factor. I'm not an expert on the details- just a passive observer for several years. But, IIRC,

I'm not convinced that Elisp-the-language is really the limiting factor. I'm not an expert on the details- just a passive observer for several years. But, IIRC, Elisp recently got some kind of cooperative async stuff. Even before that, my understanding was that there are a lot of legacy architecture issues with Emacs, from its GUI model to the actual text data structures, that contribute to to latency/slowness. I think a full rewrite in any language would have likely brought about a better UI experience.