Hi, thanks for your response.
I've just received a response from the New Gens developer. Her it is below. I will be trying this solution today.
=================================================================================
Hi,
This is a problem that often occurs with HD characters. It is usually caused by the number of polygons that need to be rendered in the scene exceeds the upper limit of the system can handle. This upper limit is usually determined by the amount of video memory on your graphics card. When the number of polygons that need to be processed exceeds the upper limit, the rendering process will "freeze".
So the idea to resolve this problem is to optimize the scene and try to reduce the number of polygons that need to be rendered.
I'm assuming your scene only has your character and NG9. Then we can make changes from the following two places:
1. Render SubD Level of the character.
Select the character in the scene, double-click the name of the character in the Parameters pane, select "General > Mesh Resolution", and find "Render SubD Level (Minimum)" in the parameter list on the right.
2. SubD Displacement Level of NG9.
Select NG9 in the scene, then go to the Surfaces pane, and select "Genitalia" under New Genitalia for Genesis 9. "SubD Displacement Level" can be found in the parameter list on the right.
Whenever the rendering is "frozen" (you don't need to wait for hours, just forcibly end the rendering when you wait for a few minutes and find that the rendering window is not updated), we can change the values of the above parameters, assign them smaller values and then render again. We need to keep trying to find the best combination that will ensure that the render will go smoothly while maintaining the quality of the final render.