Thanks much for the thorough response. Very helpful, but can you comment any more on the difference between "processed" and "exported?" Would it be fair to broadly associate "meshing" with exporting and "lighting" with processing?
All Hosts - Invisible geometry is not processed
vs
SketchUp/Rhino Enscape 3.4.3 - All geometry is exported.
What I called "export" is everything that we have to do with the host system.
We export the object hierarchies, transforms, visibility (if applicable), geometry, materials and more from the host system. We store that information in a data structure which enables us to detect changes to enable the live updates.
Then all of this is sent to the renderer where the "processing" happens. I'm not sure of what exactly happens here, that would be more for Clemens to answer. Basically the geometry, materials and everything is parsed into various caches and data formats to enable rendering.