Aaahhh.. OK..
55% of processor usage...

Yup, that's probaly (errm- make that possibly) due to disk swapping.
Poser trying to make itself  "look good" by using "Virtual Memory" rather than actual RAM.
I often get the same effect if I use Poser (P5/6) for more than 1/2 an hour.

Poser doesn't release memory for changed textures, deleted figures etc. properly. (especially the textures).
Saving, exiting Poser and restarting the reloading often solves this ('cos then the unused textures don't get re-loaded), and some of them are HUGE (far more than is neccesary for most renders).

One way I've found to get round this (which sometimes works):

Load everything you need into a scene. (Props, figures, etc.)
Delete all textures  (Via the Mat room.).
Save, exit, restart.
Set up the scene, pose the figures, move the props into position.
Re-apply the textures....(slowly, manually)

All, of course, with incremental saves all along the process..
For B/G figures/props, consider the option of reducing the testure size (in a 2d app), and using that instead (If the texture is 3000x3000 you could probably get away with using 512x512, or the equivalent ratio, depending on the original ratio).. Even for mid-ground figures, a 3000x4000 (or whatever) texture is totally OTT. Those should only be used for extreme close-ups...
Poser is a memory hog (and stubbornly refuses to remove unwanted textures)...

I don't think I'm making cohesive sense here. I hope you get the gist. I need to go beddy-bye...

Cheers,
Diolma

(burble, burble, mumble - I know there's a solution to this, just wish I hadn't drunk so much beer tonight...)