One of the big problems of editors like emacs and vim is that they haven't had means for background processing for years. And no, multithreading is not hard if

One of the big problems of editors like emacs and vim is that they haven't had means for background processing for years. And no, multithreading is not hard if you design for it. It is very hard if you need to add it as an afterthought. Some people would even say threads are easier then async.