You are indeed right. I had understood that actual preemptive threads had been added, but it seems that for now it is still cooperative and requires explicit yi

You are indeed right. I had understood that actual preemptive threads had been added, but it seems that for now it is still cooperative and requires explicit yields. Note that elisp has lexical scoping now, but it will be years of course before all packages will have been updated (and for many things you still want dynamic scoping).