A nice Gotcha (Unix Power Tools, 3rd Edition)

26.6. A nice Gotcha

NOTE: It's not a good idea to nice a foreground job (Section 23.3). If the system gets busy, your terminal could "freeze" waiting to get enough CPU time to do something. You may not even be able to kill (Section 24.11) a nice'd job on a very busy system because the CPU may never give the process enough CPU time to recognize the signal waiting for it! And, of course, don't nice an interactive program like a text editor unless you like to wait... :-)

-- JP