What is my printer's problem? 40 seconds/page

[politicat]

It's a Brother 1440 laser printer. I'm running it through my USB port (not networked, though it's no faster when networked.)

I'm running 10.3.whatever is current on a PB 1GHz GB RAM.

Brother advertises itself to print 15 ppm with a G4. Instead, this thing lags between pages, up to twenty or thirty seconds. (The page itself prints in 3-5, which is expected with a 15ppm.)

I have reinstalled the driver. What next??