I have noticed that when my poser renders hit transparent clothing and hair the render times take a big dive.  If the portion of your render is really slow at these areas of your render, then there is little to do except wait.  On the other hand, all you have to do to change the poser shader material to a Vue material is to double click on the material and click on the "simple material" tick which will remove the shader to it.  Then you can use Vue to change highlight and shadow colors.....it might speed things up.

PM me if you want screen shots to know more.