[anaerobicover]

Indeed. It does not need precisely multithreading, but at least asynchrony, which is to allow side tasks to not block the main function of editing text. I have low familiarity with emacs internals, but I can assume there is an event loop, which is a basic form of this.

Perhaps this needs be used more, or there is another mechanism to be developed allowing tasks to be interrupt/resumed in priority service to the editing functions. A key example may be mode line refresh: this certainly must happen on the main thread, but it ought not block other more important items.