It depends on the AddOn and what it does. Obviously, an AddOn like the Grid Tool will make an impact, creating quite a few additional pieces. Or the IFC one, creating invisible structures, practically another file within the file. Let's not go into RoofSurfacers and the similar ones
My favourite recently is PolyCount ... managed do cut a file from 675K to 250K polys. Considering it's a whole island, not bad
😉
Djordje
ArchiCAD since 4.55 ... 1995
HP Omen