I have noticed something like you describe too, but on the PC.
I'm using a Fritzbox, and the PC is connected with a LAN cable. The data delay increases (I saw 30 seconds and more, you can verify that when you check the laps counter in the telemetry data after you passed the start / finish line).
When the pc and the second device is connected through an android mobile hotspot I have absolutely no delay. So it seems, that in my case the Fritzbox is causing the delay. Maybe some flood protection or just a slow packet handling.