parallel port frequency?

hey, just wondering, anybody know;
on a parallel port, the input pins, how many on/off's can i send into the port pr second without the computer skipping a signal?

why?

simply put, i want to build an rpm counter useing 5 holes drilled into a flywheel, with a LED on one side and a Light detecting diode on the other, so every time a hole comes between the 2 it sends a signal to the computer, (and no gap means no signal)

using Qbasic i want to program it to basicly say, "every 5 on's = 1 rotation" (and subdivide into 5ths for acuracy)

but I don't want it to start skipping signals at higher RPM's, and for simplicity sake I don't want to build a seperate devise that would work as a buffer...

so yeah.

how many times per second could I send an on/off signal to a input line of a parallel port before it will start skipping?

thanks!