I will have to think about this. My networks are small. Less than 100 computers at each network. Having looked at the issue further, I don't think the problem is the network as in copying over. I believe that the main slowdown is 1: deleting temp files on login and 2: installing Firefox profile updates and things like that on login.
What I am going to do first is change the setup so that temp files are deleted on logoff and I need to find a script that will allow me to calculate how long each line of code is taking to run.
I am going to be looking at buying impero software that will allow me to update flash player, firefox, java as well as all windows updates and this will eliminate the problems of updating firefox, although it won't fix this specific issue as the firefox profile needs to be updated on login as the profile is user specific.
It was just interesting that several people in this thread mentioned copying the kix scripts across. I might do this as I don't update the script more than once a month I would guess, and I certainly don't update the kix executable more than once every two years. But I am assuming that if the kixtart script is running and the running of the script is taking a while on the netbooks, then its the actual script that needs to be optimised and not copying the kix files across as obviously the script has already been "copied" across.