There's something you should experiment with your card. I did this for mine (11Gb RAM) and I found that a bucket size raised up to 512 was perfect. If I'm not wrong, lower  (such as 64) values are for CPU-based renders.

My scene contains a pair of shoes, a chair, the hair prop and a Vic4-equivalent (with 6x 4K bitmaps plus the bump versions), all with SubD at 1, plus a 2k HDRi bitmap for the lighting, and it took my old system 9 seconds to push everything to the video card.
My feeling is that given the fact that your system is really newer, something is slowing it down (HD access, PCI-Express bus, or whatever)
Note that I've installed my Poser and all its runtimes on a dedicated SSD drive.

𝒫𝒽𝓎𝓁

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👿 Win11 on i9-13900K@5GHz, 64GB, RoG Strix B760F Gamng, Asus Tuf Gaming RTX 4070 OC Edition, 1 TB SSD, 6+4+8TB HD
👿 Mac Mini M2, Sequoia 15.2, 16GB, 500GB SSD
👿 Nas 10TB
👿 Poser 13 and soon 14 ❤️