Yeah, IDL Renders in poser can go past 8 hours to render for me but i'm also rendering at HUGE sizes (6000x8000 / 48MP). Here's some tips to drop those hour long renders to minutes with using IDL.
*Lower your Raytraced Bounces. A setting of 2-4 should do just fine unless you have a specific need for more.
*Remember to DELETE any AO NODES in the material room on every texture in your scene. This will make or break your render in terms of rendering times. You need to open the MATERIALS TAB and go check every each texture used on every figure/prop, select the AO NODE/S and hit DELETE. AO is a way to fake lighting while IDL is the real thing so there's no need for AO NODES.
*Transmapped Hair will also add a good 30 minutes to an hour on to your render even at smaller sizes. Make sure you select your hair and any props added onto the hair (some hair has props that are also hair), click the PROPERTIES TAB, and UNCHECK 'Visible in Raytracing'. The hair will still look ok.
A typical full screen size render will take me about 10-20 minutes if you do all that instead of hours. The trade-off with reducing the raytraced bounces and removing raytracing from the hair is that it's not going to look as good however the times are a lot better and the quality is still very good.
Hope this helps!