I've got some good experience with pdflib when it comes to speed of pdf-generation, even for large files. I was excpecting the same speeds from princexml as for pdflib, as both run natively on my linux server (they're not just php-classes). When generating a 1 page pdf with text and graphics, I see a 4 second time lapse between begin and loading of the document in the log file? Is this normal? The conversion itself doesn't seem to be long...
Mon Apr 16 19:17:30 2012: ---- begin
Mon Apr 16 19:17:34 2012: Loading document...
Mon Apr 16 19:17:34 2012: Converting document...
Mon Apr 16 19:17:34 2012: finished: success
Mon Apr 16 19:17:34 2012: ---- end