I just wanted to put this suggestion out to you and perhaps it is easy to implement on the code/programming side.
Currently the game generates and stores 1000's of NPC activity (kills, attacks, etc) emails in game. Not sure how often the NPC are spawned but it seems like it is all recorded and stored in players in-game mail. For 100's of players per BF and 100's of emails per player, and dozens of BF's that must be a LOT of unnecessary emails and notifications. That must using up some server RAM? The NPC activity emails and notifications are totally unnecessary.
Perhaps if you removed the NPC notifications and emails it would help fix the laag?
Let me know what you think or if this is a totally silly idea.