LGTM. I suspect that it would be better to have fewer/larger query pools in the vulkan backend, but we can cross that bridge if it shows up in profiles.

@JMS55 mentioned this on matrix too, but I'd need to look at the specifics (and how expensive they were). For mesa at least this is 8 bytes read back from the acceleration structure so I would be surprised if this is the main bottleneck (especially since my current plan is to combine this in a build command which is not very fast itself),

It's not the cost of the copy as much as the driver overhead of managing a lot of tiny pools (and maybe the per-pool memory overhead). The recommendation is generally to group things into large-ish pools but to be honest I don't know how impactful it is.

I think I'll add it to

Yeah this is something we can stress test once I start the actual RT work in Bevy and have something to measure.