Iray is a VRAM hog, but you can drastically cut down memory usage without sacrificing the visual quality of your final print or artwork. Here is a step-by-step optimization workflow to keep your renders firmly planted on your GPU.
Step 1: Global Settings & Diagnostics
Before changing the scene, change how DAZ handles textures globally and look under the hood.
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Turn on the Log File: Go to
Help > Troubleshooting > View Log File. Keep this open or check it right after a render starts. Search forCUDAorVRAM. It will tell you exactly how much memory your scene is taking and if it failed to fit on the card. -
Instancing Optimization: Go to
Edit > Preferences > CMS. Ensure your Cluster and Content Management Services are running smoothly, as DAZ relies heavily on instancing to save memory.
Step 2: The Biggest Culprit — Texture Compression
Textures take up the vast majority of VRAM. A single 8K texture set on a Genesis 9 character can completely tank a mid-range GPU.
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Go to the Render Settings pane and navigate to the Advanced tab.
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Look for the Texture Compression thresholds.
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Change the Medium Threshold and High Threshold settings.
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Recommended: Set Medium to 512 and High to 1024 (or 2048 if you need extreme close-ups).
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What this does: It forces Iray to compress textures that are further away from the camera while keeping your main subject crisp, saving gigabytes of VRAM.
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Step 3: Downscale Background Textures
You rarely need 4K or 8K textures for an environment asset that is 20 feet away from your character or blurred out by depth of field.
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Select background props in your Scene tab.
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Go to the Surfaces pane.
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Look for the Base Color, Dual Lobe Roughness, and Normal maps.
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Click the thumbnail of the image, select Browse…, note the size, and use an image editor to downscale it to 2K or 1K, or use a DAZ plugin like Texture Compressor if you own it.
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Alternatively, just remove maps you don’t need for background objects (like high-resolution cutout maps or micro-normals).
Step 4: Master the Power of Instances
If you have a scene with multiple identical objects (e.g., a forest of trees, a crowd of people, rows of chairs), do not copy and paste them. 1. Select your target object.
2. Go to Create > New Node Instance...
3. Duplicate this instance as many times as you want.
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Why this works: DAZ only loads the geometry and textures into the GPU memory once. Ten thousand instances of a tree will take up virtually the exact same VRAM as a single tree.
Step 5: Tame SubD (Subdivision) Levels
High subdivision levels smoothly round out geometry, but they exponentially increase polygon counts right before the render fires.
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Select your characters or complex props.
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Go to the Parameters tab and look for Mesh Resolution.
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Check the Subdivision Level Rendering parameter.
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Often, figures are set to 3 or 4 for rendering. Dropping a Genesis figure from SubD 4 to SubD 2 can slash millions of polygons from the scene with almost zero visible difference in the final render, unless you are doing a macro close-up of their eyelashes.
Step 6: Memory-Efficient Geometry & Hiding Assets
If it’s not in the camera frame, it shouldn’t be in the GPU.
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Don’t just turn off the “Eye” icon: Closing the eye icon in the Scene tab hides it from the viewport, but Iray might still load it into geometry memory.
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Use Scene Subsets: If you have a massive environment, delete the walls, furniture, and props that are completely behind the camera.
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Instance Optimization flags: For items completely out of view, change their Render Powered setting to
Offin the Parameters pane under Display.
Step 7: Optimizing Sub-Surface Scattering (SSS)
Skin shaders use Sub-Surface Scattering to look realistic, but SSS calculations are memory and compute-intensive.
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If you have background characters, select them and go to Surfaces.
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Find the Lighting Model or SSS settings.
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Turn down the SSS amount, or switch their skin shader to a simpler plastic/matte shader if they are far away. They will still look fine in the background light, and your VRAM will thank you.
