[XeTeX] include graphics: filesize difference

[Stefan Schulze Frielinghaus]

Hello everyone,

I'm trying to include a JPG picture into my LaTeX/XeTeX document. The  
picture itself has a file size of 108KB. While compiling with  
PDFLaTeX the file has a size of 132KB. but when I compile with XeTeX  
the file has a size of 596KB. With XeTeX I tried both "include  
versions":

\includegraphics{frame.jpg}
\XeTeXpicfile frame.jpg

But the filesize is the same. Why is there such a huge different  
between PDFLaTeX and XeTeX? Does anyone have a workaround?

Best regards,
Stefan