>>531438961
it's basically a multiplier on the performance tax you pay. Bigger maps = more stuff/animals = more lag. If you play on ice sheet the performance hit should be negligible in theory, opposite goes for jungle and the like. You can easily test the impact by just generating some maps of different sizes, adding pawns, raids, etc and noting TPS
I dunno about the ai issues, I don't remember ever encountering problems with that but I haven't played that much on big maps recently...