slow IP based printing

Has anyone had/fixed a problem with slow printing from IP based printers? When we installed the printers (various printer makes and models too, it's not just related to one brand) they all worked just fine and responded normally. It seems that over time, that response has slowed down greatly. One printer takes several minutes to even respond and then if you are printing multiple page documents, it takes that same time between pages printed. I've ruled out network trouble. And, as much as it pains me to say this, WIndows machines still print to these printers fine with normal response time.

The four brands of printers we use are HP, Xerox, Ricoh, and Brother. I've recently found a KB article that supplys new HP drivers and we are trying those now, but that still would not remedy the other brand of printers (at least I wouldn't think so). The response time is the worse on the HP and Xerox brand printers though.