Component's Kb Resize

Hi, I really like to create my own components in low poly and after that save them in a small size file. I’ve noticed that in each version of Sketchup i started to make them biger, even a simple rectangle so I tried to make a new template deleting Sophie and the materials, but that doesn’t worked as I expected.
For expemle, if I open an old 50Kb component made with Skup 7 and afterthat I try to save it again without touching anything the resize goes to 300Kb or more!; It doesnt matter if i copy-paste in a new file or if i save it in an old type of version, the result is the same.
Anyone knows what I’m doing wrong? Or it’s just a problem with the new versions? Thanks and my apologizes for my english.

Not sure about the other versions, but in SU2015 you might find that a Classifier schema is loaded in your model - which will affect model size.
If that is the case and you don’t need the schema, create your own template.