> 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 ter

> 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.