Well, I can say it's significantly better than when the feature first came out, but it's still too slow, especially if you have something like 100 intervals or more. I actually have a toggle in the app to turn off the feature because of it. What's your use case and what are you seeing?

Yes, the new running metrics are working great for me. You need a watch series 6 or later (or SE). Make sure you ask for permission for the new types and your using HKLiveWorkoutBuilder. I'm calling enableCollection on the HKLiveWorkoutDataSource, but I don't believe that is necessary.

Thanks for the additional information. It was an outdoor run with a series 6 watch. Are the metrics collected by default and added to the workout or do I need to enabled them (I've tried both)? My min deployment target is 6.1. Does that matter? Thanks, Jeff

I don't have a Headers phase in my project either, but enabling the new build system did not solve the issue for me.