I would like to understand why, when we save a SLDDRW file as PDF on computer A, the PDF file it comes out about ten times larger file size as when we save the same file on computer B.

The options are set the same in both cases.

We are doing "Save as PDF" and not "print to PDF" in both cases.

Could it be because computer B is Solidworks Premium and computer A is Professional?

Could it be because computer A is set to "view PDF after saving"? (Hard to imagine, but who knows...)