elapsedTime delay on device

I am trying to use elapsedDistance from the getActivityInfo() method to detect a lap turn on a swimming app. The elapsedDistance is mainly correct when testing on a real device, but it seems to take some time (somewhat between around 5 – 12 seconds) until the watch app updates it. Does anyone know how big this delay usually is? And is there a better way to get the elapsedDistance in real time?