Pace when running
I've bought my Spark 3 yesterday and took it for a first run today. I have a question regarding pace that is reported by the watch. It seemed to be extremely inaccurate. For example in the middle of the run I significantly increased speed but Spark reading show no change in pace and started slowly increasing current pace after some time. Than I reduced speed to merely jogging and watch was still increasing speed and than after a while started to slowly decrease it.
When I came back home I've uploaded run to TomTom muSports and Endomondo and to my surprise pace is displayed very differently in both although same source of data was used (pics attached). TomTom data seems to be in accordance with what Spark showed during the run while Endomondo is much closer to real life pace.
How can I make any pace based training when Spark 3 displayed value is so wrong/delayed?