Some advice i can give you with bryce renders that i have picked up from this forum and trying things out myself.

Poser figures:: if you can't see things like teeth, tongue, legs, feet, shoes or any parts you can't see select them and delete them in bryce.

Lights:: you will find the more lights you use the longer your render will take.

If you have a lot of trees in the scene try replacing them with 2d ones, trees cause a render to take longer.

Render settings:: There is no need to use anything Super with an RPP(rays per pixel) setting of 4-16, if you need to use the Premium setting you don't need RPP above 16 and remember every one of those Premium Effects you tick adds to render times.

While having a render going you would be best not using other apps or have anything running in the background like Anti virus, firewall or anyother app that will use ram/cpu.

I have opinions of my own -- strong opinions -- but I don't always agree with them.