We've being doing some work to speed up the logons to a terminal server farm. During our investigations 21 seconds of the logon was taken up by the 'Slow Network' detetion routines. This pings the profile server several times to identify to speed of the link, because the client couldn't ping the server (ICMP was blocked) it tried several times and then opened a file to calculated the network speed. All of this took 21 seconds!