I mesured the speed of printing using version 2.50e and 2.09 and i didn't notice that version 2.50e is slower, it is in fact a little bit faster than 2.09.
Version 2.05 is more than two years old and i don't have a copy of it to try it, but version 2.09 is quite similar to 2.05 except that version 2.09 runs in user-mode.
I checked if we have any speed issues raised by our customers, I found one, and it turned out to be related to the printer installation time under XP and not to the printing timing itself.
I suggest that you submit a sample application that reproduces this issue to firstname.lastname@example.org
to check it.