Quote from: Nerimash
Some highly populated realms, as well as some realms in highly populated Battlegroups, are currently experiencing performance issues during peak playing hours, which, depending on the realm, can occur both inside and outside instances. This is caused primarily by high concurrent Icecrown Citadel activity, the start of Arena Season 8, the release of the new Vault of Archavon boss encounter and the "Love is in the Air" seasonal event.
To help address some of these issues, we've applied a hotfix to optimise certain database requests during the weekly maintenance, in addition to a variety of other related adjustments. We will continue to monitor the affected realms and will be making further adjustments to continually improve performance where possible. We know the performance issues have been a frustrating inconvenience for the players on these realms -- we very much appreciate your patience while we implement additional short- and long-term solutions.