My watch seems to be struggling during the first 15 mins of an activity but then sorts itself out? It is though the watch is trying to do something that is using up all its processing power until it either completes it or gives up? interestingly both times it has done this it has corrected after exactly 15mins.
If I start an activity listening to a spotify playlist the first thing I notice is that the playback though my bluetooth headphones keeps cutting out - I had assumed this was just poor connection to the headphones but holding the watch up close to my ear does not help. What I also notice at the same time though is that my pace is way out - saying i'm running 12min miles rather that 7. Both of these faults rectify simultaneously - the music payback stops breaking up and the pace corrects and it stays fine until the end of my run. If I look back at he GPS data afterwards the trace is inaccurate during the issues - not following the roads for example. GPS data is for the period where music playback is fine.
One thing I've just thought now it that he playlist I am listening to is quite large - 80 songs - so maybe its taking a while to index or something?
Another thing that may or may not be related is that I don't run with my phone so I suppose my the watch is also using energy trying to find my phone? The latest run I did the watch seemed to start behaving after i received a "livetrack failed" notification - obviously I know livetrack wont work without the phone but again maybe the watch is using resources trying to find my phone?