I don't mean adding threading to existing functionality, and I mostly wouldn't want that. I very strongly prefer emacs' behaviour of queueing up my input events and processing them deterministically regardless of how long it takes to get to them over eg. the JetBrains behaviour where something can happen asynchronously with my input events that can change their meaning depending on when it happens.

What I mean is having threading capabilities available for things that want to (and should) use them. AIUI some support for that was added in emacs 26, so it might already be good enough.

The relevance is that EXWM is single threaded, so the window management blocks when emacs does. I don't find that much of a problem with EXWM but I doubt it would fly for a Wayland compositor, though perhaps the separate server used in that emacsconf talk sidesteps the problem.