HP 75 and the PIL-Box

[Michael Fehlhammer]

Today I copied a lot of files between an HP 75 and a PC, connected through a PIL box. It was an incredibly tedious task: a single file of 1000 bytes took about 20 seconds in average ( both directions ) ! I remember the HP 71b to accomplish that one order of magnitude faster!
I tried two PCs ( Windows Vista and 7 ), two PIL- Boxes and two HP 75 ( C and D), always the same result. My PIL-Boxes are jumpered to support 115 kbs baud rate.
Any ideas why the HP 75 / PIL-box combo is so slow? Or did anyone experience a significantly higher speed ?