Not every room will have mechanical equipment in it. In fact, not every room will have boundaries (check if there are any unplaced or unbound - if the area !> 0).
Try to reduce the geometry efforts (element.location instead of element.geometry). You could also look to decrease the amount of resources required for the entire graph by reducing the amount of nodes, which can be done with functions created in design script, python, or even custom nodes.
Short of that, post your full dyn and rvt files.