Depending on your GPU card, you'll have to find the 'sweet spot' for 'vols & buckets' size to give fastest Superfly rendering. If scene complexity gives a blank (*) or 'render fail' message, reduce your many  'v+b' setting by binary stages towards the (typically) 64 preferred by CPU-only...

Um, you may have to enable SCUDA / CUDA, too, but I cannot remember where that lives...

*) I've been caught a few times by camera being outside Poser ground's solid sky-dome, but all the lit lights were inside. So, just an unlit wall: Oops...