On a DECwindows workstation, the DECW$SERVER_0 process and DECW$TE_xxxx need to
get some amount of compute time to service the keyboard/mouse input and display.
By boosting the relevant process priorities to 31, I was able to monitor/control
a looping process at 30.
Since you don't say how the priority was set, you need to beware that
in internal representation priorities are backward, so if you changed
the priority from K-mode code and wrote the priority with 63, it actually
would mean priority 0.