I can show you my own, humble experience. I'm not an expert with the Material room, that's why the 3rd picture doesn't look exactly the same as the 1st and the 2nd.
The first two are based on EZSkiin3, using the Cycles plugin, with a slight difference: we have to lower the gloss effect with Poser12, for the rest both are 100% the same.
The lighting: a clamshell + one light above, all three are area lights, nothing around the scene except the backdrop.
My computer: an old Intel Core i7 at 4.3Ghz, the computations done using my RTX2080ti, each time using the official "Ultra NonBranched (GPU)" setting.
Don't forget that Poser12 has a new optimization system that is not present in Poser11

Each picture has been computed at 459x800px

Poser 11: 60"
Poser 12, using its default GTX mode: 34"
Poser 12, using its new RTX mode: 19"
Poser 12, using my shader (I'm using a second layer for the anisotropic/gloss effect): 32", and it takes longer without the second layer...

𝒫𝒽𝓎𝓁

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(っ◔◡◔)っ

👿 Win11 on i9-13900K@5GHz, 64GB, RoG Strix B760F Gaming, Asus Tuf Gaming RTX 4070 OC Edition, 1+2 TB SSD's, 6+4TB HD
👿 Mac Mini M2, Tahoe 26.5, 16GB, 500GB SSD
👿 Nas 10TB
👿 Poser 13 and 14 ❤️

𝑀𝓎 𝒢𝒶𝓁𝓁𝑒𝓇𝓎