[XeTeX] Size of PDF files produced by XeTeX

[Bruno Voisin]

With identical input, save for the choice of fonts, pdfTeX produces  
output that seems generally significantly smaller than XeTeX, at  
least on Mac OS X.

For example, I'm working on a 14-pages note including 2.9 MB of  
graphics in the PDF and JPEG formats. In pdfTeX, using the Lucida  
Bright/NewMath fonts, the note is a 4.1 MB PDF file; in XeTeX, using  
the Lucida fonts for maths and Verdana for text, the note becomes a  
7.3 MB PDF file. I do not think the Verdana fonts account for the  
additional 3.2 MB, all the more so since, adding the [draft] option  
to the LaTeX graphics package so that the figures are replaced by  
placeholders, the size becomes 120 KB in pdfTeX and 380 KB in XeTeX.

To summarize:

- with pdfTeX, 120 KB (draft) ans 4.1 MB (final);

- with XeTeX,  380 KB (draft) and 7.3 MB (final);

whereas the difference between draft and final is the inclusion of  
2.9 MB of graphics.

Does this mean the included graphics, in JPEG and PDF formats, are  
first uncompressed by pdfTeX and XeTeX then recompressed at the end  
of the process, and that pdfTeX compression would be more efficient  
than that offered by xdv2pdf (which possibly calls Quartz routines)?  
And in that case, is there some special invocation of xvd2pdf that  
would make the compression more efficient?

The problem here is that the note was meant to be emailed or put on a  
ftp server for download, so that size matters, eventually. I'll  
probably just burn a CD and use standard mail, as requested by the  
recipient, but I was wondering whether a better solution existed.

Bruno Voisin