Printing from clipper program

I have clipper program runnig on win NT.
Printing to matric printer EPSON LQ850 is a big problem. It goes, but it’s very very slow. One page is printed in 2-3 minutes. Printing on page priner like HP deskjet 600 is normal. It looks like it has problem with printer buffer. I switched settings to “print direct to printer” and RAW type.
Does anybody have any idea how to solve this problem.

Thanks!
Andrej