Ah. I suppose it was probably the combination of Still/High GI (perhaps unnecessary since the v3 clouds are a background element here), and cloud quality settings. I have made an optimized version of the .tgd that renders with almost identical lighting (it would be hard to argue there is lower "quality", the difference is incredibly minor), and with actually less noise, and takes less than half the time. TGD and image example attached. The original settings you had took 4 hours, 25 minutes on my dual Xeon machine, while the optimized version attached took just 2 hours, 4 minutes (and again has less noise). Primarily what I did was lower the cloud GI setting one notch (you could probably even get away with "low" stills setting and save even more time), and then reduce cloud ray-marching quality to 0.5 (default) but increase voxel scattering quality (in cloud GI settings in Render node).
- Oshyan
