Render settings advice?

Hi there,

I need some advice on my render settings. I have a fairly big comp (planar tracking, roto with motion blur, transforms, film grain a.s.o) with a resolution of 4800x2700 at 16 bit float.
My machine is a MacPro 6.1 (trashcan), 64 GB RAM, 12 core CPU, Dual D700.

I've tried different stuff with simultaneous branching, multiple frame rendering, dual gpu for Metal...
I've pre-cached the most complex stuff (filmgrain, roto masks) but it's just painfully slow at 1 fps.
It uses all 12 CPU cores but just 1 of 2 GPUs.
Even rendering via Render Node didn't help.

Is there anything I can do in terms of better settings? Is simultaneous branching and rendering multiple frames a bad idea?

Thanks

Fusion will always only use 1 GPU for rendering. It can use the second one to accelerate the display, but at present, it can only use one for calculation. If all of your CPU cores and 1 GPU are active, then probably your settings are good. Fusion is doing a lot of work, and there are only so many things that can be done to speed it up. I usually don't start complaining until a comp gets into the 8 seconds / frame range.