It seems like connections on nostr are not too "stateful". All messages sent to the socket could be sent each in it's own separate connection, concurrently, handled by different caching replicas of the same relay or different threads of the same relay. There's no session/user-level state to coordinate and synchronize btw replicas/threads that could harm scalability.   

 Yes, I think you're onto something.  

NostR = notes and other stuff transmitted by relays.
Nost = Notes and other stuf.   

 No I mean that relay architecture and performance and scalability wouldn't differ much if it was plain http server.