Current behavior
When a material is modified during IPR, the entire image is re-sampled and rendered again. This can result in very long waiting times, especially in large and complex scenes.
Feature request
When a material is modified, only re-render the objects affected by that material change instead of re-sampling the entire image. Unaffected areas should retain their existing render results whenever possible.
This would significantly improve IPR responsiveness and make material tweaking much faster, especially in large scenes.
For example, when adjusting the roughness or color of a product material, the IPR could keep the already converged pixels in unaffected areas and only update the pixels that are actually affected by the material change.