Hi there. Thank you for maintaining this awesome package.

I have some questions

1. Have you used any of the registration features (local ICP, or fast global FGR) and encountered any noticeable performance issues when running on an iOS mobile device? I imagine some of these algorithms would be quite computationally expensive to run every n frames, so perhaps downsampling would be helpful here.

2. In the example app, I notice that you use SceneKit's SCNGeometry to render the point cloud. I tried it out and the UI seems responsive with 196,133 points in the provided file! I'm curious if you have encountered any issues in rendering larger point clouds, and whether Metal would be a more suitable choice if there are more than N amount of points. I check out Apple's point cloud visualizer example in which they use Metal to do so.

3. I imagine using the C++ backend might squeeze some extra performance vs. using PyKit, do you happen to have suggestions or know of how to build and interop with Open3D C++. Do you think it's worth the extra effort to write C/Objective-C wrapper vs. using PyKit?

Thank you!