I have started noticing a trend with Revit when adding items to systems.
Basically, it happens when I have a run of pipe or ductwork and evyething is connected together and put on a system. If I try to add a VAV, for example, to the system and if it has at least one connector connected to either pipe or ductwork Revit will freeze up for a looooooooonnnngggg time! *HINT the extended spelling of "long" to emphasize the effect*
Anyway, I was wondering if anyone had any insight as to why this might be happening. It is a bug in the code for sure.