Sieve extprograms socket vs. direct execution

Hi, I'm hoping to get some clarification of the differences between calling a script using the Sieve extprograms plugin execute method via direct execution or using the socket feature.

Being naive, I see the socket option and think that way you tell Dovecot to spawn a daemon and I think that's going to be far superior in performance. But if that really was the difference, why would direct execution even be an option? (And doesn't the daemon still have to spawn a new shell every time if the target is a shell script? Does that defeat the purpose of having a daemon?)

So I don't really know what the difference is, and under what circumstances you'd want to use one or the other.

Can someone please help clarify?