I thinik it's about AI pathfinding , because when you start the siege they already have commands like Infantry is using the siege equipments, and Infantry is assaulting the walls , those commands given by itself are working fine and no lagg , I have more fps on sieges now than on the field battle lol , but when you give order that Infantry is following you or holding the position or what is the worse CHARGE , their pathfinding is bad and they all stuck charging and causes drama drop fps , but only when full 500 man on the battle i think...