Slow serial communication under Windows XP

[Max Boidi]

Hi all,
I've a problem with the serial speed comunication under Windows XP
Professional.

I use the serial API's to communicate with my cash register at 9600
bps speed.

Under Windows 9x it works fine but under XP it's about 10 times
slower.

Using a direct access to the serial port with API's, can I improve my
communication speed without setting threads priority?

Thanks

Max