Comment 33 for bug 998087

PDFs are vector format (with the option embed raster graphics "images" in them) so they don't have an inherent resolution.

It's more likely that a "light" PDF doesn't have images, or other "advanced" PDF features, that need converted into something else (PDF supports features that Postscript does not). Or possibly the "lighter" PDF doesn't embed fonts, or doesn't embed as many or as large fonts.

It's *really* impossible to guess without an awful lot of work from someone like me, and an awful of help from you to narrow down the printer's bug, and assess if there is a workaround.