When using UIView.drawHierarchy, older CPU performs far better than newer CPU

Hi all,

My app uses SpriteKit views which are rendered into images for various uses. For some reason, the same code performs worse on a newer CPU than on an older one.

My A13 Bionic flies through the task at high resolution and 60FPS while CPU usage is <60%, while the A15 Bionic chokes and sputters at a lower resolution and 30FPS.

Because of how counterintuitive this is, it took me a while to isolate the call directly responsible--with UIView.drawHierarchy commented out, both devices returned to their baseline performances.

 guard let sceneView = skScene.view 
 else { return }

let size = CGSize(width: outputResolution, height: outputResolution)
return UIGraphicsImageRenderer(size: size).image { context in
    let rect = CGRect(origin: .zero, size: size)
    sceneView.drawHierarchy(in: rect, afterScreenUpdates: false)
}

Does anyone know why this is the case, and how to fix it?

I tried using UIView.snapshotView, which is supposedly much faster, but it only returns blank images. Am I using it wrong or does it simply not work in this context?

sceneView.snapshotView(afterScreenUpdates: false)?.draw(rect)

Any hints or pointers would be greatly appreciated