Mouse lag in viewport(Iray)

Mr_Fluffkin

Hi! When i switch the drawstyle to iray in my viewport, my mouse starts lagging like there are 0 ressources left to handle the mouse cursor smoothly. I figured out that i can fix it by reducing the "CPU Load Limit" by 1 core(in Render Settings -> Advanced -> Scheduling: from 24 to 23 in my case). But i wonder if this should be neccesary and the best way to fix it? Or are there other/better solutions?

System is i9-12900K, GeForce RTX 3080 Ti

hansolocambo

With 12GB of VRAM you should be full GPU.

Let the CPU Load Limit to the maximum. My guess would be that you did not activate the GPU in Daz ?

Render Settings > Advanced > everything should be ticked here except CPU Thread Affinity.

I don't see why Iray preview would slow down your mouse (depending on the scene complexity of course). My rig is MUCH older than yours and all works fine.

Mr_Fluffkin

hansolocambo said:

With 12GB of VRAM you should be full GPU.

Let the CPU Load Limit to the maximum. My guess would be that you did not activate the GPU in Daz ?

Render Settings > Advanced > everything should be ticked here except CPU Thread Affinity.

I don't see why Iray preview would slow down your mouse (depending on the scene complexity of course). My rig is MUCH older than yours and all works fine.

Oh wow, deactivating the CPU device checkboxes and leave only the GPU ones checked really did the trick. Thanks so much Han, everything's super smooth now again! :)

hansolocambo

Well good news ;) Still weird though. Iray is not an hybrid CPU+GPU like Renderman. So if your CUDA was ticked, then it should have worked on full GPU. Iray switches only if the scene's geometry and textures cannot fit the Graphic card's VRAM. I keep CPU ticked and all is fine except if scene is too big.

So... I'm glad it works. But there's something wrong still. You can't just untick CPU as you might need that if you render scenes bigger than 12GB. :/

Hopefully someone more technical than I will come around ;)

Cheers.

Mr_Fluffkin

Yeah, it's quite weird, I didn't expected that behaviour either. But my system isn't throttled down or anything like that. It's a new computer and it renders super fast at all. It's just that as soon as i switch to iray, the gpu and cpu useage immediatly jumps to 100% that not even the mouse runs smoothly(if both devices are checked). It's like a 100% priority for the daz task and every percent of power is put into daz. But unchecking the cpu device really made it. It doesn't even render longer with gpu only and everything else is running supersmooth. I'm not familar with the technical background of daz, but it definetly seems to use my gpu AND cpu if i check both devices. I can see that in my task manager. All 24 cores are used to a 100% and the gpu as well.

I'm quite interested in the technical background and if unchecking the cpu is the proper solution, so i hope someone can explain how it works and what the cpu is used for. I tested the same render with gpu only and with gpu + cpu, the one with both was like a momentum faster, not even noticeable. So i wonder what the cpu is used for...