Aha! Thank you for the explanation. Have you corrected the mistake already?

By nodes. Do you mean points placed on building shapes? It would explain why the areas are simplified and why they don't line up with the actual shape of the buildings as shown in the satellite images. 

Besides the apartments, I have been messing around with rural areas and I assumed Ai was used to assign simple shapes or bounding boxes to represent structures. It bothered me that they didn't line up but it also explains why the program slowed down as I added more detail.

If I understand what a node is, this is why a building with a complex shape is represented by a box with 4 corners.....or nodes??

The design is intentional?