Inspecting with the Frame Debugger, it seems that there are several large (200 MB) MSAA textures. Is there any way to control multisampling (like with SCNAntialiasingMode in SceneKit)?

Yes, exactly. Full screen on the Pro XDR blows up Dirty Memory Footprint to 2000 MB.

Thank you, I've filed FB11305740. There really needs to be a way to control the frame rate on macOS for non-AR use cases. Regarding the renderOptions, my reason for trying to disable these is that a simple default box scene seems to be using 500-900mb memory. I found a Stack Overflow topic which recommends disabling some options to improve RealityKit memory footprint. If these are already disabled, what can I do to decrease the memory usage? Surely 500mb is not expected for such a simple scene?