I have a slight concern that as great as the new UHD cache is with direct light, its amazing! just as not great it has become with indirect light.. yes it takes more passes and that's fine. But we have several scenes where if we were to do animation on these jobs, which is very standard.. exterior tall building with shops at the bottom kind of job, we would never be able to finish it while maintaining an image quality anyone would pay for.
simply put, in slightly low light areas the noise is very very persistent, and 30min -1hour a frame (which is too high) is no where near enough to give us enough passes to begin to clean this up.
Noise is very visible even after 150 passes, decent though ,but also 2-3 hours a frame on a 6 core xeon.
Yes the scene we use is super heavy, not ideally optimised from a geometry point of view etc.. but this is often the reality when working with cad imports etc, just don't have the time to sit around creating utopia unfortunately.
EDIT: I think we may have found out why we got SO much noise in this particular scene... lights... IES lights... delete them, and we get a cleaner image after 30 passes than we ever did after 120 passes.
scaling is what I am referring to, since the core things that makes corona great, also becomes its down fall when time is a problem, there is no way to fake, turn off stuff that will speed things up.
anyway im starting to ramble here, sorry just my thoughts on a problem I'm not really sure how to "fix"