Note: A lot of this information is taken right out of Daz 3D’s Getting Started in Iray tutorial video on YouTube. If you learn better from videos, you might find that helpful.
The Problem
I’ve seen repeated questions about improving performance of the Iray drawing style in Daz Studio 4.10 viewports. Imagine my surprise when I was watching the Getting Started in Iray tutorial video and found a wealth of information already available on the topic!
Photo realistic rendering in the Daz Studio viewports can slow down even some of the fastest computers out there because Studio is trying to interactively create a “final” image and has to recalculate light paths, material interactions, shadows, and such each time you move your view or relocate content. This can cause people to feel like the program is really sluggish and/or that it causes everything else on the computer to grind to a halt every few seconds.
Interactive to the rescue!
Technically, NVIDIA Iray has two modes that it can render in. The one that is the default and we’re most familiar with is Photoreal. With only a few exceptions, this will be the mode you want to use for final image rendering.
There’s another mode called “Interactive” which has many of the same features as Photoreal. However, because it lacks support for computationally expensive features like subsurface scattering and caustics, it will generally render much faster.
Rendering Devices
On the Advanced tab of your Render Settings, you have the option to select which devices (CPU or graphics cards) can be used to perform Iray renders. There are separate selections for Photoreal verses Interactive. Personally, I don’t mind if Studio has to fail over to my CPU for a large final render, but for Interactive mode that we’re using on viewports, it’s probably better to uncheck the CPU. This will also stop the Iray engine from grabbing the CPU for rendering purposes and slowing everything else down on your computer.
NVIDIA Iray Rendering Devices in Daz Studio 4.10
Render Settings
While we’re on the Render Settings, go back to the Editor tab, Render Mode and change this to Interactive. Technically you might think this would ONLY affect if you’re doing a final render. However the Daz Tutorial indicates that Rendering Style and Draw Style are linked in some way; so it’s best to set this setting to Interactive as well.
Choosing between Photoreal and Interactive modes
Just don’t forget to switch it BACK before you do your final rendering!
Draw Settings
Next is setting the drawing style for your viewports. There’s a good chance you don’t have the Draw Setting tab open in Studio. Go to your Window menu -> Tabs and select Draw Settings. You can dock it wherever it feels most natural to you.
Also, you will need to repeat the steps below for each viewport that you’re using Iray in. Most of the time, I will set my Auxillary (Aux) Viewport to Iray so I always have a rendered looking image to refer to even if I’m using Texture Shaded on my main viewport. Draw Settings changes focus for each active viewport that you click on; so make this changes in any viewport using Iray.
Draw Mode
Go to your Draw Settings tab, Drawing section and change the Draw Mode from Photoreal to Interactive.
Setting the drawing style on the current viewport
Response Threshold
When you’re using Interactive Draw Mode, Studio will pixelate your image when you start moving your view around and then will resolve it back to a rendered image when you stop. Response Threshold tells Studio how sensitive to be to view changes before it changes to the pixelated view. The lower the number, the more quickly it decides to pixelate the image. Higher numbers make the Interactive rendering engine work a little harder, but if your graphics card can handle it, it’s probably less annoying for you. You may need to play with that value to find a number that works for you.
Manipulation Mode (optional)
If you find the pixelated image still feels too sluggish when you’re navigating around your scene, you can choose how the content display changes when the Response Threshold is exceeded. As I mentioned, by default it pixelates the image, but from the Draw Mode tab, General, Manipulation section, you can choose to use either wireframe or solid bounding boxes instead. This is another option for those who are using slower computers or if you have a very large scene with a lot of detailed content.
Choosing how Daz Studio draws content while moving the view
Conclusion
I hope this information is helpful to someone. The Tutorial video covers a few other pointers on using Iray as part of the scene setup process. I highly recommend it to anyone getting started in using this tool.
Karl's Journey 
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