Guys who know the secret of fast rendering in DAZ?
"Give your scene enough light!"
That's Iray's top and dirty secret. This renderer
really dislikes indirect light, mirrored reflections, and translucent objects. In these it sprinkles what is called "sand" or "grain" on the renderer.
So the main secret is to use a wide dynamic range (which can be done through the render to "Beauty" canvas, in the tab Render settings) and deliberate
overlighting of the scene.
Then it is corrected by the exposure of the scene in Photoshop.