I just bought this beautiful "Rio" hair from RDNA but it is taking at least half an hour to render 1 frame in the Poser 4 render without shadows. Any way to get it to render faster?

I assume you mean Poser 5 (which is what you have in the title.) I'm not familiar with the product, is it strand based hair? If so Try reducing the number of hairs in the hair room (In each group) by at least half. Make sure you have one shadowmap casting light pointing at the hair,(The map can be small) This is to keep the scalp from showing thru. I've found you can get the strand counts pretty reasonable by doing this. (I experimented with RDNA's Mod bob hair for Vikki) Now if collision detection in P5 hair only worked I'd be happy. :) Hope this helps.

What helps is to select every single hair part and in the properties uncheck the "cast shadow" button. that makes the render of the shadowmap faster. but i agree, good looking p5 hair is a real pain in renderspeed.

Thanks to both of you. I changed my lighting and the hair looks great and renders much quicker.