- big pdf?
- weird linetype?
- bit-map fill?
- scanned image?
Please note that Ac10 treats bitmapped fills a little bit differently than 9, especially the percentage fills in the default list. I'm not sure about all that's happened, but I think it can pay out to check how your fills display and print, along with help files and other docs.
I personally avoid percentage and bit-mapped fills as far as I can. I use grey-scale pens instead and let the printer rasterize. Much faster, and printer-independant as well.
Scanned figures have always been print-slowers, especially at high resolution (above 300 dpi) and/or if they are transformed (scaled, stretched etc) in Archicad.