How long should it take to publish a PDF from FrameMaker DITA?

We have a software manual authored in FrameMaker DITA. We are looking at around 250 pages once output. We are having trouble with generating a PDF. It either takes was too long, or then does not even manage to finish compiling. I understand this may take some time, but what is realistic here? Are there better publishing solutions for FrameMaker DITA? This is yet another frustration with FrameMaker. It just does not seem to be very robust when doing anything moderately complex.