Thanks for the tip.
But the major time consumer is the sss and the displacement on my cereal seen in close-ups.
I'm rendering pathtracing with 3000 samples max, which isn't much. And it already takes 1 h 40 per image.

I'd be totally willing to share my cereal-shader and my modular 2001 room rebuild ...

cerealCrowd.jpg

So I finally have some free time. And I'm finishing a fake cereals commercial in Octane (for C4D).
It's a short and not so performance hungry project.
But still. To render some of the sequences of that commercial would take at leat 200 hours. 200 hours where I can't use my PC. :x ...