3D dwg works nicely when ifc balloons file size

so I used to import ifc´s from the engineer for steel constructions, those balloons my file size with 30-40 mb.

Asking for a good old 3D dwg only imports 1,8 mb for the same geometry. Very much nicer. The ifc import does not recognise components as copies it seems, the only logical explanation I can find for the difference in file size.

That is not due to the IFC importer, but the structure of IFC files. IFC has no instancing, every object is always unique. What is worse, every component has its origin at the model origin point - killing SketchUp if the original model exports to geolocated coordinates.

hm. strange. The ifc file is just 1,3, the dwg is 1,8.

But the sketchup-file from dwg is far smaller (the same 1,8) than from the ifc.