I personally dont think the map size has anything to do with the lag, but rather it is the sheer numbers of players feeding information into the server. I have seen just as much lag with the big maps as the smaller ones. Just think about 500-700 players all feeding information to the server with their:
alt, speed, ammo loadout, direction, location, the planes they see and what type of plane they are, then you engage one or more and now you have to feed, number of rounds expended, number of hits, amount of damage you see (enmy has to feed damage he sees as received).
I am by no means a network or computor wize but it sure looks like this is the problem to me.
ab8aac
out