Print jobs over XP network are slow to start.

I have a printing problem which I don't understand.

I have a small XP Pro network consisting of two PC connected together via a
LinkSys BEF SX41 router. My printer is directly connected, via a usb port,
to one PC. This printer is shared so that the other PC can use it.

My problem is that printing is slow to start if I use the PC that is
indirectly connected to the printer. I have to wait a little over a minute
for any printing to start during which time you cannot use the application
that is initiating the print. There are no such problems if I use the PC
that is directly connected to the printer.

Does anyone know of a reason (or reasons) why this should be happening?

Any constructive help gratefully recieved.

Martyn.