As stated in subject. This is the thing that perplexes me the most about Poser 11 & 12, especially 12: why isn't Cycles an interactive viewport mode?

IIRC, there is something in the works.

As a workaround, if you go to the render settings, preview tab, and uncheck the "enable hardware shading" checkbox, it will show the Firefly/PoserSurface material instead of the Superfly/Cycles material. It's not as good as a real Cycles view but it can be helpful when you are trying to pose your figures so you aren't just looking at white silhouettes. Just make sure you have a PoserSurface root with your texture map attached.

An alternate workaround is to switch to Firefly until you are ready to render. But personally, when I do that, I always forget to switch back before rendering. Maybe you are smarter than me and won't have that problem. ;)

Bondware had officially announced the introduction of CyclesX last year, which I believe is fast enough to allow interactive viewport mode - assuming people have a decent GPU. However, I believe the current priority is to complete unimesh Poser, so [I assume] everything else will have to wait until that is done. I am hoping unimesh Poser might see the light of day still this year.

Even though it's a very interesting (and desired) functionality, I wish that they first correct the nasty bugs hiding deep inside the couple RTX/Cycles, especially now that they've enrolled a Cycles guru last year.
In the mean time, I'm using a preview mode using Posersurface and using a script, I switch my figures to cycles.

Or a Linux version of the Queue Manager so we could linux render in Cycles? still hating on W10

See here:

https://www.posersoftware.com/article/538/poser-update-poser-120703-improves-usability-and-material-room-performance

Supposedly, it's in the development pipeline: "Latest Cyles updates and support for Cycles X Viewport"

Thank you, that's exactly what I was looking for!