Question: Whisper Target Limit

[jrl290]

A couple of clarifications:

Is the whisper target limit per server or per user? Do all users share the same set of whisper targets on one server, or is the limit just a matter of the number of targets that one user can transmit to at once.

Secondly, how quickly can the registered targets be changed? Is it fast enough that one can expect to reconfigure the registered targets before each transmission?

Thank you