I'm currently converting my game from SceneKit to RealityKit. What's the easiest way to run an animation in which every frame I want to run custom code, similar to SCNAction.customAction which accepts a callback that is called repeatedly until the action completes?

I'm trying to convert my game from SceneKit to RealityKit. I noticed that even when the scene is static (nothing moves), RealityKit keeps using CPU. In SceneKit, CPU goes down to 0% with a static scene. With this simplest of games, RealityKit keeps using about 65% CPU: class ViewController: NSViewController { override func loadView() { view = ARView(frame: NSScreen.main!.frame) } } Is this expected or a bug? I created FB22125047.