I lag like no other in event hall. It's actually ridiculous and I just wish they never even made the map to begin with. I don't see what's the problem with leaving NPC's in every town.
Only way it'll be able to cooperate with me if I do "CTRL+ALT+DELETE" and click on "Task Manager" and click on MapleStory again. You get a few seconds of lag free time to get what you need and go out. I repeat this process like 7 times and it takes me at least 15 minutes to go in - and go out of the Event Hall.
(I do the same for Bingo and the X&O questions since I also lag there as well).
Maybe it'll work for you? It just prevents me from lagging too much to the point where I can't move and end up disconnecting.