I can see how the performance here would be extremely fast, since it's not actually doing any math during the traversal:
https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.23.3092&rep=rep1&type=pdf

Josh Klint said:
I can see how the performance here would be extremely fast, since it's not actually doing any math during the traversal:

That's maybe not what you want.
You have to factor in the latency from (usually incoherent) memory access. Better spend the waiting time on doing shitloads of math, than doing nothing while waiting. : )
(But just saying in general, not referring the paper at all.)

Crytek claims their voxel lighting is faster for direct lighting than shadow maps, but I'm not sure these numbers make much sense.

Doing a few matrix multiplications 40,000 times is going to be a lot faster than any kind of ray traversal performed four million times.

Shadow maps are limited by vertex count. Voxel shadows are limited by surface area. I have a hard time seeing any way voxels could replace shadow maps, for direct lighting.

Josh Klint said:
Crytek claims their voxel lighting is faster for direct lighting than shadow maps, but I'm not sure these numbers make much sense.

I think that's true for scenes with many lights. Then it's ‘generate X SMs each frame’ vs. ‘reuse one acceleration structure for all frames’.
Even if a trace is much slower than a SM lookup, at some point X becomes the dominant factor even in practice.
If that X is in practical range for actual games on affordable HW is another question.