RPR Uber takes an unreasonable amount of time to start rendering when using a texture for emission weight

[krzysztofKKW]

Issue

Whenever using a texture as an emission weight input, if the shaded model is complex, RPR takes a really long time to start rendering a preview. The difference is that of several times: if the preview takes 5s to sync and start rendering, it will take up to 30s with the emission weight input connected.

Steps to Reproduce

1. Set up the scene to render using RPR
2. Spawn a monkey and increase the mesh complexity using a multiresolution modifier several times
3. Assign a material to the monkey, and replace Principled BSDF with RPR Uber
4. Add an image texture to the shader for the emissive effect. A "Webdriver torso" image with black background works for me
5. Enable and set up these parameters:
   • Diffusion, some color to verify a change in appearance
   • Emission, connect the texture color to emission color
6. Create an RGB to BW node to create a mask for the emission color.
7. Connect texture => BW => emission weight By connecting and then disconnecting BW to and from emission weight, the difference in response is massive as described above.

This is especially weird when just the emission causes the preview to freeze for minutes on a complex model, while a Diffusion + Reflection + Refraction + SSS + Transmission RPR Uber doesn't cause a drop in responsiveness for more than several seconds.

System Setup

Windows 10 Pro Ryzen 5 3600, RX 6600 XT, Driver 22.11.2 Blender 3.3.1 Using both CPU and GPU for rendering

[ARozghon]

Thank you for your request

that's the issue reproduced with all added textures maps or with specific maps? could you share some maps to make a correct investigation with similar maps?

thank you