I am seeing this exact issue. I have a Windows 2003 print server (also a domain controller), Windows XP pro desktops (all updates), Adobe 6.0.1 and current drivers both PCL and PS delivering about 3ppm. I'm sending the jobs not as images, and breaking them into 20page increments has no effect on print speed. If I send the job to a local LaserJet 1200 I'm at about 12ppm. I've tried printing these jobs both from saved locally and from messages they arrived in.