Docs for the new raytracer?

I’m playing with the new raytracer and I’m definitely getting faster results, but with the speed my RAM requirements are shooting into the stratosphere. The new raytracer seems to have much steeper ram requirements, but I’m also noticing a ton of new options for controlling the raytracer. Like i can choose between auto, octree or several different bvh types and I don’t know what any of it means.
Can anyone share their knowledge of how to use this new raytracer?