One of the refreshing things about Cataclysm is the return to life of the capital cities. I remember the days of “unknown entity” in Ironforge in Vanilla and the lag that was also in Shattrath. But with Wrath we were assured that the no fly zone would help prevent the lag in Dalaran.
Sadly even Dalaran was way too small to play host to all the citizens of Azeroth without causing major lag for most people at all times of the day and particularly around late afternoon/early evening rush hour. So bad was the issue that Blizzard had to change its plans for the Argent Tournament to be hosted in the Crystalsong Forest and relocated it to northern Icecrown (did you wonder why the pre-Qs were in Crystalsong?)
However, even with the old capital cities all is not well. Sure the opposite faction are not clogging up the system and players have a choice of 4 faction capital cities, although I doubt many choose to base themselves in Darnassus, Exodar, Silvermoon or Thunder Bluff.
The cause of the problem is not numbers but their mounts. Since Vanilla, the size of mounts has grown from little mechanostriders through mammoths to massive dragons. People love their flying mounts they are able to zip around their chosen city in style bypassing the twists and turns dropping in to the daily quest givers and mailboxes and that is the problem players forget that their behemoth mount obscures the target for other players and the more people that do it the worse it gets.
Now I’m a fan of flight and mounted travel around our cities and certainly don’t want to start a campaign to make them pedestrian zones but is it really too much to ask for players to be auto-dismounted if they are stationery for an amount of time and below the roofline? Sure players would take some fall damage but not enough to actually kill them.
Not only would this solve the frustration of trying to interact with an NPC/item without it being obscured totally or by flapping wings interrupting the process (I’m looking at you mr flightform druid) but it would surely also help keep the lag down to a minimum at peak times (notice how WoW loads mounts and pets before player characters).
Another potential solution would to put a barrier around NPCs and items as happened with some of the quest givers in the pre-Cataclysm event. However, this would make then immune to attack by opposite faction players which may not be overly desirable.