prime time n.
[from TV programming] Normal high-usage hours on a system or
network. Back in the days of big timesharing machines `prime
time' was when lots of people were competing for limited cycles,
usually the day shift. Avoidance of prime time was traditionally
given as a major reason for night
mode hacking. The term fell into disuse during the early
PC era, but has been revived to refer to times of day or evening
at which the Internet tends to be heavily loaded, making Web
access slow. The hackish tendency to late-night hacking runs has changed not a bit.