Slow rendering time.
lucasnglife
Posts: 6
There have been other discussions on this topic here on the forum, but my problem is different from the others. What usually happens is that a standard render on my system (I’ll list the specifications below) takes 10–12 minutes, rendering images at a resolution of 1920x1080 in a standard scene containing objects, lighting and two Genesis 9 figures.
The problem occurs occasionally, where the scene takes between 40 and 60 minutes to render, using the same scene, lighting and figures.
I use Nvidia Iray as the engine, in photorealistic mode, with CPU fallback disabled and CPU unchecked in devices. The GPU is identified correctly.
Using the CPUID HWMonitor software, I identified differences in the GPU’s performance in both cases. CPU usage remains constant throughout both.
| ITEM | NORMAL RENDER | SLOW RENDER |
| GPU Power Consumption | 140W to 150W | ~60W |
| Temperature | ~80°C | ~56°C |
| GPU usage | 100% | 100% |
| VRAM usage | 98% to 99% | 96% to 99% |
| Frame Buffer | 69% to 74% | 2% to 6% |
| Bus Interface | ~60% | ~16% |
| 3D Usage | 94% to 100% | 56% to 100% |
There is a notable discrepancy in some itens, where even though the GPU reports that it is using 100% of its capacity during rendering, it does not utilise its full processing power to complete the task, resulting in a significant increase in the time between interactions during rendering. This problem occurs in both Daz Studio 4.24.0.4 and Daz Studio 6 – beta version 6.25.2026.14722.
The only solutions I have found for the problem so far have been to close the Daz Studio application, clear the RAM using RAMMap, and reset the graphics card driver using the shortcut Win+Shift+Ctrl+B. If that doesn’t work, try resetting the graphics card using the command (nvidia-smi --gpu-reset) in the system terminal, or, if that doesn’t work, perform a full reboot of the operating system.
I’d like to know if other users are experiencing this or if it’s just me. This problem persists even after reinstalling the software, the operating system, in both the Game Ready and Studio versions from NVIDIA driver.
System information:
Windows 11
DAZ Studio 4.24.0.4 - Daz Studio 6 – beta version 6.25.2026.14722
AMD Ryzen 7 5700X 8-core processor
NVIDIA RTX 3060 12GB
NVIDIA GeForce Game Ready Driver 610.47
64GB RAM
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Comments
That looks as if soemthing is just tipping the scene over the edge so that it no longer fits into the GPU memory, in which case you will need to restart DS to free it up. Check that you are not leaving a previous render window open as that will keep the memory used. You can see what is being used in the DS log file, near the end after rendering - Help>Troubleshooting>View Log File.
I usually render directly to the file, without opening any windows. Often, even after completely restarting the DS, waiting for it to clear the allocated memory and then opening it again, the problem persists.
I’ll try to reproduce the problem by opening a window and leaving it open on purpose.
I ran the test by rendering to a new window and left it open; immediately afterwards, I started a new render, and as you had anticipated, the problem in question occurred: the rendering was very slow, with intervals of up to 12 minutes between each interaction.
I noticed that it was slower than when the problem I described occurs; as I mentioned, I do not use the method of rendering to a new window, I only render directly to the file. In the log, I found no mention of an open window near the end of the section where the rendering ends. I used the DS 6 for this test.
Something isn't right. My W11 machine (Ryzen 7 8600G, 64Gb DDR5 RAM, RTX4070 Super) rendered a 4k image yesterday with 9 G8 characters in about 45 minutes on 98% convergence.
Your log says you rendered 3 images.
First in 9 min 30, then 10 min 30 and the 16 minutes. All rendered to 1000 iterations (as you have set that as limit).
Yes, in this log, the first render was carried out to see if the problem occurred straight away; rendering directly to a file, it completed successfully without the problem appearing. For the second render, I rendered to a new window to start the test, and the render was also completed successfully without any issues. The third render was started with the second render’s window open, and a problem similar to mine occurred; it took 16 minutes to reach 34 iterations out of the 1,000 iterations I use as standard. I cancelled the last render before it finished, as it would have taken too long to complete; at the rate it was going, it would have taken over 8 hours to finish.
Yes, it would take less time if I used fewer interactions to finalise it; it usually reaches 90% convergence. I optimise the scenes using 2K textures for the most part, as I render in FHD; I only keep a few textures at 4K, such as the characters’ skin. I can render up to five Genesis 9 characters in the same scene within a reasonable time.
Have you checked the log after a slow render, to see exactly what is being used?
I let a slow render finish completely; it took 1 hour and 40 minutes to complete. The only message that caught my eye was ‘[INFO] - IRAY:RENDER :: 1.7 IRAY rend info : CUDA device 0 (NVIDIA GeForce RTX 3060): Optimising for cooperative usage (performance could be sacrificed)’.
I use the spot rendering tool a lot; I noticed a behaviour where, after using it and closing it, it did not free up the space it had allocated in the VRAM. In the log I shared, this caused two instances where the next render failed completely, and the following was observed in the log: "Iray [WARNING] - IRAY:RENDER :: 1.7 IRAY rend warn : CUDA device 0 (NVIDIA GeForce RTX 3060): Failed to allocate 94.923 MiB for (device) frame buffer, will try allocating smaller (partial) frame buffer"
This behaviour was also present when another application, such as a browser, was open and using a small amount of VRAM; when starting the render, it allocated enough and began, but apparently the other application may have illegally accessed the pre-allocated memory, leaving DS without enough memory to complete the task as it should, and either continued rendering slowly without causing a total render failure.
It really does look as though I'm "edging" my VRAM XD
This usually happens for me if I try and render too many images without closing and restarting Daz, and it's annoying as hell. If I've rendered a bunch, eventually the renders screech to a halt, and I have to restart Daz. A render that takes over an hour can occur in 5 minutes or less if I restart Daz sometimes. Daz doesn't have a way to flush VRAM without restarting it.
@vandeci127 found a way to clear VRAM without restarting DS.
https://www.daz3d.com/forums/discussion/comment/9298636/#Comment_9298636
Wow thanks, I'll have to try that the next time things slow down. Could be a huge time saver, especially with a few of my scenes that take 10 minutes or more to load in every time I restart.
That works really well, but it would be good if they could sort this issue out in DS 6, or at least add a button to flush the VRAM.
I've trying this the last day or two. It only works half the time (approximately). But I have two instances of Daz running and switch between them doing renders. One will work over and over and the other will need exiting to desktop and even that doesn't fix it. I suspect this is also a driver issue. But even a 50% work success is better than needing to exit Daz completely.
Yeah that whole "...in the Render Settings options, next to Editor, there’s a tab called Hardware. Just uncheck the GPU and then check it again, and Daz will instantly clear the VRAM." thing seems to work when it wants to in Daz 6. It's inconsistent whether it works or not. Maybe it's different in 4.24 but I can't render there with my 5090. A simple "Flush VRAM" button would be quite handy.