Castello is a frame rate nightmare for me and my PC. I understand my PC is aging poorly but no other map puts the strain like castello.
it's because the castle bits are very large objects, which means it's hard to hide them or reduce the level of detail on them - we're working on "chopping up" the castle walls and other objects so they can be hidden or lower quality when you're not looking at them / far away. The look of the map won't change, but the performance should increase :)