Why is it laggy in Eureka?

[Raldo]

you can't really say that it's because of too many players because it's not laggy in Ul'dah or Limsa despite the crowd.

Why is it laggy in an area where nearly 150 people are all moving/attacking/etc. in one small area?

vs

Why isn't it lagging in a town where most people are afk (or are tinkering around in menus that don't affect you, so they appear afk)?

I'll leave it to you to work out the answer.

[Blokeymon]

Why is it laggy in an area where nearly 150 people are all moving/attacking/etc. in one small area?

vs

Why isn't it lagging in a town where most people are afk (or are tinkering around in menus that don't affect you, so they appear afk)?

I'll leave it to you to work out the answer.

I literally came here to post just that!

"Why is it laggy in a huge area wit hundreds of mobs and almost 150 people from different worlds, most working together in big groups and with big flashy spells and skills going off, as well as a background sim calculating mob spawns and FATE instances? It isn't laggy in my housing ward where I never see anyone."

Gee, I wonder...