What? 100ms is "human speed". When doing anything interactive the difference between 25ms and 5s is monumental. Even just for pressing confirmation buttons 5s is slow enough that you need some substantially faster reacting visual confirmation (loading animation or whatever) to satisfy humans.
5ms versus 5s is the difference between being tempted to check or think about something else or not. Multiply that option over and over with a repetitive task and anyone but your most disciplined monk is going to find themselves getting side tracked regularly.
