Having a similar issue, and I filed FB15831006, "Prohibitively high energy usage from RealityKit when idling" as an API enhancement request.

For what platform are you developing? iOS? SpatialAudioComponent requires iOS 18 and/or macOS 15. That should be fine to develop on an x86 Mac. For visionOS, you can't use the visionOS simulator however, so that would require an Apple Silicon Mac.

Okay great, devforums threw away my post when trying to reply here... Trying again. I'm getting this error too and it's super frustrating. If I could pay for GPU instances, or if I could provide my own hardware to Xcode Cloud, then this wouldn't be an issue. But now this is forcing me off of Xcode Cloud, since there's no way for it to build my project on it. Anybody else found any workarounds? I don't think I can apply msanford's trick, since it's failing generically on my rkassets bundle and won't even tell me which asset requires GPU to compile.