Rhino Save Win vs Mac

I work on both envirorments Mac and Win.
Win in the office and Mac at home.

When I save a file from the office, and then open it at home from the Rhino for Mac - without touching anything, if I just press save the file goes from 1.2GB to 4.6GB

Is there a particular reason for such difference between the two?

Thank You

Hello- Mac saves a high resolution preview image.


on a more realistic note then the preview theory:
even if this is file specific to my knowledge, it could have to to with the preview-meshing settings.
Try to save the file with ‘Save Small’ enabled. This excludes the preview meshes. See what the difference is then between mac and windows (also save small on windows)