What contributes to slowness in Cycles?

evilded777

Just learning here, but I'm asking in the DAZ forums because that's my background... and the same tricks don't seem to help (hiding unseen geometry, etc).

I see such widely varying times in render speed at the same dimensions, and I just don't know what to do to try to speed things up. Changing light bounces is a bad approach with DAZ characters....and I am at the default of 12. I see how raising and lowering that affects things. There must be other tips and tricks?

Padone

Personally I tend to render with 64 samples and the fast global illumination preset for light paths, works fine most of the times. For complex geometry hairs I set 32 or 64 transparent bounces. When I want a really realistic result or there's a complex scene with lots of refractions and indoor illumination I can use the full global illumination preset instead.

The optix denoiser is much faster, so better for animations. The openimage denoiser is better but slower, good for single images.

One important thing is the persistent data in the performance tab. If you're rendering animations then enable persistent data, otherwise textures get reloaded for each frame. If you render single images then keep it off, as this way it leaves the memory free when not used.

p.s. Apart the cycles settings, it is always better to plan your scene and use collections to hide unused or unseen geometry. Of course small scenes render faster than large ones and also take much less memory.

p.s. Apart the cycles settings, always use simplify to limit the subdivision and textures size, this is unfortunately a requirement with daz content as PAs tend to use very dense geometry and very large textures. This is similar to the scene optimizer plugin in daz studio.

evilded777

Padone said:

Personally I tend to render with 64 samples and the fast global illumination preset for light paths, works fine most of the times. For complex geometry hairs I set 32 or 64 transparent bounces. When I want a really realistic result or there's a complex scene with lots of refractions and indoor illumination I can use the full global illumination preset instead.

The optix denoiser is much faster, so better for animations. The openimage denoiser is better but slower, good for single images.

One important thing is the persistent data in the performance tab. If you're rendering animations then enable persistent data, otherwise textures get reloaded for each frame. If you render single images then keep it off, as this way it leaves the memory free when not used.

p.s. Apart the cycles settings, it is always better to plan your scene and use collections to hide unused or unseen geometry. Of course small scenes render faster than large ones and also take much less memory.

p.s. Apart the cycles settings, always use simplify to limit the subdivision and textures size, this is unfortunately a requirement with daz content as PAs tend to use very dense geometry and very large textures. This is similar to the scene optimizer plugin in daz studio.

Simplify? Is this part of Diffeomorphic or Blender?

Padone

https://docs.blender.org/manual/en/latest/render/cycles/render_settings/simplify.html

evilded777

Padone said:

https://docs.blender.org/manual/en/latest/render/cycles/render_settings/simplify.html

Thanks, found it.