Well the way the congestion stuff has always been presented is for it to be influenced by the amount of non-native players in any particular world/DC, more or less that there's a cap on the number of visitors allowed at any given time. Hence why Aether tends to be completely inaccessible to outsiders during peak hours like afternoons/evenings. 20-60 alts from outside would most certainly be affecting it then in that case. But Daralii mentioned that not being the case, and if so then I agree, nothing really should be done about these guys no matter how annoying they are or aren't to anyone.