I am not sure how much this actually speeds things up; it seems to make some difference, but I do not have benchmarking software installed to actually test.
In my Applescript that I use to activate VPC5.0, I include the following line after the activate...
do shell script "sudo renice -20 `ps -x | grep 'Virtual PC 5.0' |[Note: Enter on one line with a space before the 'grep' command]
grep -v 'grep' | cut -f1 -d' ??'`"
sudo visudoand then add the following line to the file and save it:
%admin ALL=NOPASSWD: /usr/bin/reniceWhat this does is allow any user in the admin group to run renice as root without entering a password.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020102143717912