Speed tracking

Hi, Im trying to break the 30 knot barrier when wing foiling, but I have a feeling my speedometer is not very accurate. Im using a Coros Apex 2 Pro right now and it feels like its taking average speed over like 20 seconds intervals. This makes the max speed unreliable I think.

Does anyone have experience with this and is there any good app for measuring speed with like 2 second intervals?