[pstricks] PSTricks and the size of pdf files

[Paul Smith]

Dear All

I have produced a 13 pages presentation with beamer class, which
contains only  three simple PSTricks pictures and I am surprised with
the relative large (not huge, though) size of the pdf file (ps2pdf +
pdfcrop). Is there some way of optimizing the size of the pdf file? Or
the source of this size inefficiency is pdfcrop?

Thanks in advance,

Paul