Queue size, threading used for session message Handler?

Hi @PGriffith (if it's in your scope)
Is there any queue size limit for Perspective Session Events message handler ?
For one type of message, are there processed in sequence or in parallel ?

All other message handlers are sequential per handler--I'd expect Perspective sessions to do the same (but perhaps separately per session, like Vision clients).

If IA doesn't give a definite answer, some experiments would be welcome.

Sequentially, "aggregated" by project.