Grrr I should make a post in rants and raves about a**hole IT guys not wanting to face the fact that it is thier problem and not the copier.
If you can print THAT PDF fine with Citrix not in the equation, then I would TOTALLY eliminate the copier (firmware/settings/HDD/etc..) and focus on Citrix. Tell him to update the Citrix client on the problem workstations, totally uninstall the driver (KM undelete utility for kyrcera/mita website is very good) and install a fresh copy.
Then have him go to C:\windows\system32\spool\printers and delete any file in there (make sure viewing hidden files is enabled so you can see the .sho files). If ther are any files in there make him feel like an dumb by tellig him deleting those files and using an undelete utility was routine maintenance on any print server, and I just ASSumed he did that

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Deleting any files in that folder and using the KM undelete utility on print servers to eliminate any orphan print driver and help files will help with the printing slow issue on any print server.
I've had numerous problems with Citrix and ALL of them have been resolved on their end. Having him update Citrix client and totally reinstalling print driver has fixed a lot of weird issues. Problems where one user could not install a print driver, you could get as far as the last "next" and the status bar moving all the way across then rolling back and giving an error. Problem where users with multiple printers switching from one printer to the other it hold settings from previous printer to the new printer (staple/duplex when u didn't ask it to). Problems one of those small reciept printers and our copier printing garbage out unless they logged out and back on before switching form one printer to the other.
Bottom line Citrix is notorious for printing issues.