[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.