For a panorama viewing application, I'd like to show multiple panoramas side-by-side inside a UICollectionView. The single panoramas are represented as cube-mapped textures. The rendering is done using Scene Kit.

When using a single SCNView, the application performs fine. When I instantiate multiple SCNViews side by side, the frame rate for all SCNViews plummets to almost one frame per second. GPU and CPU utilisation is almost zero.

The arrangement of the single SCNViews can be seen below:

I observed that each SCNView spawns a separate render thread. The problem persists regardless of weather OpenGL or Metal is used as render API.

How could we resolve or at least debug this issue?