All new phones replacing a several year old model exhibit the same characteristics you say here. Of course going from 6s->XR is faster (several generations of

All new phones replacing a several year old model exhibit the same characteristics you say here. Of course going from 6s->XR is faster (several generations of newer cpu), has a better camera, and that brand new battery lasts a long time. Your old phone was about 3.5 years old. You could have gotten a new 6s and it probably would have had most of the characteristics you say, because it wouldn't be throttled due to an old battery. Or just replace the battery. It would hold a charge a lot longer. The only thing that wouldn't really be different is the camera.