I've asked this on other poser-related forums, but I'm interested in hearing more tips on how to increase speed and quality in the output render.

I already have the firefly renderer set to a separate process, and I've given it multiple threads for more power. I've turned down or off texture filtering for most textures. Yet I have some complex scenes that just refuse to render after days of false starts or completely failed starts.

increasing render speed usually means decreasing quality in any 3D renderer. most of the variables are there in the render settings. ya may hafta settle for a lesser-quality render that's easily identifiable as a poser render. I thought I saw a thread here or elsewhere yesterday on what to do, but I couldn't find it. you know the drill: reduce texture size, convert figures to objects, increase shading rate, reduce ray-trace bounces, always set "post-filter" to 1, reduce shadow map size, reduce pixel samples, reset texture filtering to "none" for all materials, reset shading rate on all objects. unfortunately the result of all this is not pleasing to the eye IMVHO.

Quote - I've turned down or off texture filtering for most textures.

Don't turn it off if you want speed. "Fast" is the best choice if you want speed.

Fast filtering is quicker than no filtering?

so turning it off might look nicer than setting it at "fast", but "fast" is faster than "none" or "quality". maybe "none" is the slowest of the three.

How do you convert figures to objects?

You may find that your more complex scenes will render more safely with internal rendering instead of trying to render in a separate process (I did).

jjroland what do you mean exactly?

don't mean to hijack this thread but, how do we make sure (or apply) the multithread rendering in poser? is that through the bucket size?

Nope, it's in General Preferences -> Misc. (I think) in the bottom left corner of the dialog box.  Note that adding extra threads is only really valuable if you have a multi-core or multi-processor machine.

jj, export the figure as obj. check everything but "morph target". delete figure. re-import obj with everything unchecked. AFAIK it cuts down on RAM usage.

Can you still move and pose it that way?

No
When it arrives as an object you cant pose it again, saving as an object usefull if you want to keep a group of characters that can be used for filling in a scene.

I see.  Thank you both.

Converting figures to object help nothing the rendering speed, it is only useful for setting the scene.
Poser becomes slower and more slower increasing the number of figures, if you convert a figure to an object or prop you can move very fast the object to the required position of the scene making the scene setup easier. Once you have the scene it will not make any important difference in rendering time if you use figures or objects.
What makes the rendering process slow are the texture size and transparencies, the number of polygons has not too much importance. Transparencies are the worst and if you have transparency behind other transparency is demoniac (something that is common with hair).
Other thing that makes rendering slow are big objects, I don't know why by any stupid reason Poser takes more time to render a big six faces cube than a small 10,000 polygons object!

What makes renders slow down for me is a) ray tracing with multiple bounces and b) very large numbers of polys that are close together when ray tracing is on e.g. complex hair.