Frostmourne (high pop) was laggy for the first 12 hours after patch release but since then it's fine so Blizard is probably slowly getting everyone fixed. For those who may hate me for having a currently stable server, in BC we had 4 months of almost un-raidable lag and guild GMs actually petitioned blizzard to wipe the trash from the raids so we could actually attempt bosses during the small windows of laglessness.