Probably faster than the 3B1 was in real life. Being an educational
institution in NJ (Rutgers) we had all sorts of AT&T stuff donated to
us, 3B2's, 3B5's, and 3B20's.
The 3B2 was the first machine that I came across I think with a soft
power switch. Amusingly, the thing would not let you shut it down
unless you were root (apparently, you don't have power switch privs as a
normal user).
Of course, this was in contrast with the 3B20 which you powered off by
turning a knob and then holding a button down for three seconds. Yep,
phone equipment. Those who ever dealt with things like real Western
Electric 303 "broadband" modems recognized that behavior. You commanded
loopback on them the same way.