RealityKit game keeps using ~65% CPU even with empty scene

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.