Reason #64634 for World of Warcraft being down for the majority of US east coast prime time:
The reason for the maintenance is that we have identified that one of the problems causing multiple disconnects revolves around the boat system in the game. Specifically, the boat that travels between Menethil Harbor and Auberdine was causing errors that impacted stability for the entire realm.
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We continue to investigate other unrelated performance issues, but we believe this measure will help improve stability for our players until we can fully resolve the boat issue and place it back in the game. Thank you for your patience during this time, and we look forward to seeing you back in-game!
Riiight….