Very slow time to first pixel with a small exterior scene

[Alex_M]

I have a small exterior scene with some Forest Pack scattered objects that starts rendering really really slowly on GPU. I've timed it and it takes 3 whole minutes for the render to start. Not only that, but when I stop the render, Max freezes for 2 minutes. The same scene starts rendering in ~25 seconds with the CPU engine and Max is usable immediately after I stop the render. I know it's because of the Forest Pack scatters, because when I hide them, the scene starts in ~35 seconds and stopping it doesn't freeze Max for minutes.

Is this considered normal for exteriors with Forest Pack rendered with the GPU engine? I can't imagine using GPU for exterior projects if I have to wait minutes for the render to even start. This is pretty unfortunate since GPU is much faster at rendering foliage than CPU. Anything that can be done to speed things up?

[Muhammed_Hamed]

Hi Alex_M ,

Is this considered normal for exteriors with Forest Pack rendered with the GPU engine?

No, it is not normal, we are aware of this slowdown. I have a few cases logged that devs will get into after V6 is released.
Time to first pixel is something we plan to invest in, I will add to the GPU roadmap soon. Although I'm not sure how much this could be improved or how hard it will be.

Your scene shows big difference between V-Ray and V-Ray GPU, probably more than anything I have logged. Is it possible to upload the scene for us, it will be used for our internal testing, whenever devs get to this task

Best,
Muhammed

[Alex_M]

Yes, I can send you the scene. I've submitted a ticket with number 42478. You should see the wetransfer download link in there. Thanks!

[Muhammed_Hamed]

Hi Alex, thanks for sharing the scene

We will investigate this soon. I have collected a few cases on time to first pixel, your scene is the best contender

Best,
Muhammed