Unbiased don't work so ... With Presto interactive in viewport it is extremely slow and causes mouse cursor jumps (with low priority on both) with lowest on both works even nice and in darkroom with lowest works now much bettergiannis wrote: I am not sure about the expectation here but true/unbiased volumetric lighting is time consuming. I don't think though that it is as slow as you are describing but this really depends on the expectation.
Perhaps, you can lower priority for either the CPU or GPU?

