A blink lasts 300 milliseconds.

Kevin Lawler

Marshall Bowers

For most computing applications this is an eternity. If your application depends on interaction, then take full advantage of any anticipated delays. A command-line interpreter returns output to a human only a line at a time, so it doesn't matter how slow the parser is. Even the worst strategies will produce execution times orders of magnitude below the measurable perception limit.

Bad parsing takes less than a millisecond and cannot be perceived. What this means is that all time spent on optimizing the compiler for this case is absolutely wasted.

Delays are often based on different thresholds of human perception. For websites this is maybe 50ms, for video games maybe 1ms. Mobile apps are somewhere in the middle.