Revit print directly to A1 plotter - speed varies GREATLY for same file and page

Hi guys,
I am still testing this behaviour but in a nutshell:
When we print set of drawings from a revit file using plotter settings for "speed" they are done in few seconds per page...great
Another day same file, same page, same printer settings and page takes 7-8 minutes to print, as if printer is set to high setting and is taking a lot more to print.

What the hell?

Same settings, nothing is being changed, it varies from day to day.
Is it a printer or Revit causing issues? Ill test print from PDF to see what happens.

Anyone experience something like this before?

Regards,
Milos