Re:
Less than 3% quicker.
Looking through my Strava for similar timed segments shows a much wider spread over just one of my 26" bikes, let alone over all of my bikes.
Are you a racing athlete, if so then yes 3% is significant as you'll know what your best is.
Not one, then it is easily day to day variation, ground conditions, tyre pressures, wind direction, gps differences, when you last ate..