Large orders stuck in Print at Home queue

Hello all -- searched around the site for a previous discussion of this, and checked the PAH documentation, but didn't see anything about it: we're in the middle of our Nutcracker presale and are suffering from some very large scalper orders (which is a whole other topic of conversation, unfortunately) that are getting stuck in the PAH queue.

It's not consistent -- some even larger orders are going through fine. Does this have something to do with the relative use of server memory at the time that the PAH server is trying to process the PDF? Do I need to move this conversation to tech support? Has anyone else experienced this?

thank you!!