If you're building e.g. a PS1 prompt replacement, you'll want to start, gather data, output the PS1 prompt and exit in less than 0.016s at most. Any slower and

If you're building e.g. a PS1 prompt replacement, you'll want to start, gather data, output the PS1 prompt and exit in less than 0.016s at most. Any slower and the user will see a visible delay. If you're on higher FPS monitors, the budget shrinks accordingly. At 60fps you'll have 16ms, at 480fps you'll have 2ms. The same applies for any app that should feel like it starts instantly.