It’s a combination of everything. Attributes, embedded library parts (including textures), viewpoints, views, layouts (a major contributor, which is why our kits are bigger as everything is pre-linked), publisher sets, it all counts.
For me personally, file size is a non-issue with the amount/price of hard drive space these days. Particularly for solo projects. When you’re talking about libraries, teamwork projects and BIMx files, as well as actual projects that may have too many polygons, etc, then size becomes more of an issue as it directly affects your experience.
As ARCHICAD continues to develop and the internal database becomes more complex, the file sizes should be expected to grow also. That’s just my 2 cents. At 50Mb I think that’s pretty small actually and there’s not much to worry about.
When people send us files for ArchiCHECKUPs, they get up and over 1Gb each!
Cheers,
Link.