I have an app that uses ARKit with RealityKit using ARBodyTrackingConfiguration. I also perform CoreML detections on CVPixelBuffers from ARFrame.

It worked perfectly without issues until around iOS 14.5. Since then if I run AR experience for longer than 20-30s with body detection and CoreML processing detections at the same time, I get big jump in CPU usage (from 80-100% to around 200-220%) which lasts for few seconds and produce lagging/stuttering video footage on device screen.

What I've tried:

• I checked for memory leaks in instruments and can't find anything wrong there. If I disable either body detection or CoreML processing, the issue disappears.

• I tried putting CoreML processing on .utility qos (which gives less detections per second) but it still didn't help.

• I never process more than one frame in CoreML (I check if previous processing was finished).

• It's not thermal issue because it appears even if I start the phone after night of not using it, it still appears after around 20-30s

Here is the screenshot from Debug Navigator