One more post from some further investigation... I find the problem appears to be Catalyst specific. Running the same AVFoundation video capture code for macOS uses roughly 5x less CPU than the same thing in Catalyst.

This is reproducible with Apple's own tutorial project: https://developer.apple.com/tutorials/sample-apps/capturingphotos-camerapreview 85% CPU usage on an M2 Pro with a Catalyst build! Even if you don't do any processing in the ouput delegate, then the CPU usage is still really really high! I measure the battery life for video capture as about 7 times better on a similarly specced Windows machine.

Similarly, I'd like to control things like the exposure and power-line frequency on UVC cameras

Unfortunately, even meddling with the relevant user plist files doesn't seem to be sufficient to turn it off... group.com.apple.secure-control-center-preferences.av.plist If the application's reactions-enabled and gestures-enabled-default are set to false, the high CPU usage from the gesture recognition is still incurred.

@Jang-Soonwon By default, Apple applies Reactions and there's no way to turn it off. So, this could potentially related: https://developer.apple.com/forums/thread/743518

@AvdLee If you're concerned about AVFoundation perf, maybe you'd like to boost and comment on this issue: https://developer.apple.com/forums/thread/743518 AVFoundation uses nearly 50% CPU by default because of Reactions, and there's apparently no way to turn it off!

Oh wow, the battery life on a MacBook is absolutely terrible on video capture apps because of this. Did anyone find a way to disable it yet?

Just to link back from here that this maybe also affects dotnet MAUI still: https://github.com/dotnet/maui/issues/26650 And that also the separator reappears when the window is moved - even if it has been set to hidden: https://feedbackassistant.apple.com/feedback/18161892