I suspect this is a hardware rather than a network problem.
Love my HP2600N color laser. It spits out pages at about 15/min, more than ample for me.
Now I am doing Christmas cards & envelopes, non-standard sizes.
I send two documents – a card and an envelope – to the networked printer.
I feed the card in through the front slot, it prints, but then I experience a delay of about forty seconds until the mechanism grabs the envelope.
Of course, since it’s manual feed and alternate stock (card-envelope, card-envelope, …) I am spending a great many 40-secondses staring out of the window at the equally dismal scene outside. 
Does anyone know of a quick solution to this problem? 80 seconds times 300 pairs is – too much time to waste.
I have not tried doing a bulk mail-merge and two print streams from the tray, because I’ve tried that before and always seem to put the wrong card in an envelope.
I should add that if I’m manually-feeding regular paper, as in a double-sided print job, the turnaround is good; I do not experience anything like a 40-second delay.
Oh yes, during the 40-seconds, the motors are turning; that is, I can hear the sound of the mechanism that drives the rollers, or whatever they are.
