As far as I investigated, using components in SU does not affect the size of the resulting KMZ file that much. In fact, I have just made a test and exported a SU file (with lots of components) into kmz. The one using components came out bigger than the one that I exported after exploding the components( and purging the components from the browser). See attatched file.
I'm not too much in scripting but to my understanding, xml format (simple text files) cannot support components at all (Tomasz could confirm this - or anyone who regularly export into Kerkythea).
Rename your kmz file to zip (that actually it is) and you will see a kml file in there. That's the geolocation info only. Now there's also a folder in there called Model or what (I'm too lazy to check) inside which there's a collada file (with dae extension) and the images if you used any. Both files (the dae and the kml) can be opened in a plain text editor and you will notice that in the collada file there's no info about components or anything.
So as a final "verdict" - with excessive geometry instead of photos you cannot keep the size of a kmz file smaller when it comes to a certain level of details and complexity. I made some Gothic churches with ribbed vaults and window tracery and ended up with GE almost being unnavigatable when playing around with placing them.
When a model loads, first the geometry loads and then the images (sometimes one by one). So you are already able to see things and navigate around while it is still loading. If you use excessive geometry, this will not be the case. A colonnade however should really be modelled for instance - you cannot substitute all detailing with images. You need to find a healthy balance between them.
I hope I haven't been too exhaustive π
doric_coloumn.zip