This post is to hopefully save others some headache. There is a known issue with the Scatter node in C4D while running under OS X Sierra using a Pascal based GPU (Currently the GTX 10XXX series). According to OTOY tech support, it's likely an issue with the current Nvidia drivers and the way C4D handles OpenGL. The configuration involves at least:
OS 10.12.X
Nvidia driver 378.05.05.15f01
CUDA 8.0.83
C4D R 18.XXX
Problem Description: If you increase the number of instances in the Scatter node to the point where the interactivity and screen refresh bogs down, the interface remains sluggish even when you reduce the number of instances down to what should be a very responsive level. The interface remains sluggish even after deleting the Scatter node, or in new C4D scenes. The only way to return responsiveness is to quit and relaunch the C4D application.
OTOY knows about the problem and example scenes have been submitted to the developers.
Hope that's helpful!