emacs-async

That "99% of standard usage" is the kicker, isn't it? The greybeards who opposed multithreading since the beginning tend to say that the remaining 1% of use cases is best done in an external process, ideally not even written in Emacs Lisp, so that Vimmers and the rest of the free software community can benefit. The GNU Global you mention embodies that ideal exactly. I suppose if you still want that program to be written with Emacs Lisp, you could use async.el (https://github.com/jwiegley/emacs-async/) and there's finally an use-case for the threads: it'll be relatively safe to run those 16 threads only in the external Emacs-process.