Two Timing Rules That Eliminate Loading Spinner Flicker in Flutter Apps

A common Flutter pattern uses a boolean flag to show a loading spinner during API calls, but this causes a flickering effect when responses arrive in under 100 milliseconds. Research by Jakob Nielsen established that actions completing below 100ms feel instantaneous, meaning a briefly flashed spinner creates visual noise rather than useful feedback. Developers can fix this by introducing a reveal delay — typically around 140 milliseconds — so that spinners only appear if an operation actually takes long enough to be noticeable. A second rule requires that once a spinner does appear, it stays visible for a minimum duration, around half a second, to prevent an equally jarring instant disappearance. Together, these two timing rules — a delayed reveal and a minimum display duration — address the root cause of spinner flicker without changing error-handling logic.