Quote - Would you say that deleting off camera objects world be even more advantageous than just making them invisible with respect to speed and memory use?

There's no advantage with respect to speed, as far as I can see. There should be a reduction in memory use, although you may not see the full benefit until you've restarted Poser.

Quote - In Poser Pro 2010, if a whole character or prop is invisible, it doesn't seem like Poser loads their textures into the calculations when rendering the first time - which could speed up the initial render. But, if you had any part of their body showing, I think Poser calculates their entire texture collection. Back in the Poser 5 era, I could have sworn Stewer did mention that making elements invisible that were out of the camera's view did help lighten rendering processes.

If you think about it, the renderer needs to assume that every visible scene element is going to taken into account during rendering. Even if the camera isn't pointing at it, it may feature in reflections, or any other indirect effect that can now be achieved in Poser. But if you turn off an element's visibility, the renderer knows from the start that it can ignore that thing. Hence the resultant speed-up. Now that later versions don't load unique textures for invisible items either, there should be an improvement in memory usage also.

When I was doing the tests I mentioned in my first post in this thread, with the plane in front of my avatar figure, I noticed that the rendering slowed down when it reached the point where the glasses were - as it does when they're visible. It's as if it had to stop at every pixel and check whether whatever was behind the plane ought to figure in its calculations, and that took extra time. What's more, the time depended on the nature of the material, even though it was hidden. The renderer couldn't "look ahead" well enough to work out that the things behind the plane would never have any bearing on the final render.

In conclusion:

Make any scene elements that have no contribution to the final render invisible; it will speed up the rendering, and may help memory usage too.

(Edited for clarity. I hope.)