90d4b823d7
For the first bounce we now give each BSDF or BSSRDF a minimum sample weight, which helps reduce noise for a typical case where you have a glossy BSDF with a small weight due to Fresnel, but not necessarily small contribution relative to a diffuse or transmission BSDF below. We can probably find a better heuristic that also enables this on further bounces, for example when looking through a perfect mirror, but I wasn't able to find a robust one so far.