Finally I tried pdflatex and it worked great! Just create a little .tex script that uses /includegraphics{file1.pdf} for every single page, and the output file is small and in very good resolution.
[Editor's note: The above is exactly what was submitted by the anonymous contributor, and I couldn't ask any clarifying questions as he/she did not include their email address. Based on some web research on my part, it appears that you'll need to install TeXLive-teTeX in order to get pdflatex. However, I haven't tested this out by actually installing the package myself, so you're on your own on this one -- but I thought the hint interesting enough to merit posting anyway.]

