No, it is local, and I've seen some of the delays on the CFO's machine and it could just be a small network hiccup where it takes about 20 seconds to open an email with a 5MB attachment, but more importantly they are just not used to waiting AT ALL and want instant access to their email.
When you say disable the mailbox, you are talking about disabling the archiving from Enterprise Vault as opposed to Exchange, correct?