I think the title of this should be changed, at the moment it's click bait. It should be something like:
CUDA Ray Tracing 2x Faster Than RTX when Rendering Spheres
As far as I can see, this renderer can't do anything else except spheres (and maybe planes).
It's no bad achievement to beat a general purpose production renderer at one specific thing, but a renderer that can only do spheres is just a hyper-optimized toy, and here it's being presented as far more than that.