Back in the day we banned using animated xlock to lock your screen. The Sun workstations in the lab ran the X server local and picked a random other machine to run the window manager and clients when you logged in. (Which is kind of an odd way to do it when I think about it now, but also cool that it was possible.) However this was all running over shared 10 Mbps ethernet with probably 100 machines and only 2 or 3 segments. This all worked fine until a few people use animated xlock running remotely over the shared network.
> ran the X server local and picked a random other machine to run the window manager and clients
Are you sure they were full workstations and not more dumb terminals (just enough processing power to be an X display) with all your logins being to a central beefy server (or one of a few) rather than some random machine?
If that were the case then an animated xlock would potentially chew up an unfair amount of CPU time as well as clogging the network spitting the results out to your local X display.
