RAM use with Iray

Slartibartfast

Hi! I'm new to Daz3D from last week, and I've been greatly enjoying my time with it so far. I even bought a Platinum Club subscription, and as part of my first purchase afterward, I got Mage Tower Iray. Now, this is a pretty straightforward model. It's a somewhat big room with a couple of bookshelves, windows, and a fireplace. The books are individually modeled, but simple. The install is 568.2 MB. So far so good. 

I created a new scene and added the major Mage Tower Iray pieces to it, except for the individual props. I then did a test render. Much to my dismay (and surprise) Daz started consuming more and more RAM until it had taken every last drop I had available, and then it started rendering with my CPU, essentially making my PC unusable until the render was done, which took much longer than it should have because of this. I have a powerful i7 7600K with 32 GB RAM and an overclocked Geforce GTX 1080, so I wasn't really expecting this kind of issue. 

I've noticed this in other scenes too. Even a single Gen8 model can really cause a large amount of RAM usage, and it slows down the application considerably, especially when using the Iray preview. Not to the extent that Mage Tower Iray does, but still.

Is this normal? Can I do anything about it except turn everything in the scene that isn't visible to the current camera invisible? Even that seems to be a limited solution. I'm currently rendering a test image that features less than half of the model, and Daz is using 20.5 GB of RAM. I had to set the Daz executable's affinity to free up one of my CPUs just so I could write this post, and that slows down the render even further. 

I'd appreciate any help.