the problem is the way you sned the print.  if you send over one document with multiple pages, it will do a continuous print.  If you send each label as a seperate document,  it will backup forthe next label.  The Zebra 2400 printers are the same thnkg and do the same thing.  To speed up large print jobs,  I use Crystal Reports to create a continuous feed.
 
Hope it helps,