Lag from tall buildings?

I have z levels on and tall buildings also more locations. Both from within the game if that makes a difference.

Every time I pass a 3 story brick house I get serious lag and slow downs.

Do you have experimental 3D vision on?
Just the vision - it is seriously unfinished. Other z-level code is fine, but vision is very inefficient.

Yea I do. It’s probably that isn’t it.