1024 Samples Per Pixel, 2 minute, 50.632 seconds to render. MIS with Power Heuristic. With multiple scattering. Expected path length is about 11 bounces.

1024 Samples Per Pixel, 1 minute, 37.595 seconds to render. MIS with Power Heuristic. With multiple scattering. Expected path length is about 4 bounces.

1024 Samples Per Pixel, 40.087 seconds to render. MIS with Power Heuristic. With multiple scattering. Expected path length is about 1 bounce.

1024 Samples Per Pixel, 1 minute, 32.740 seconds to render. MIS with Power Heuristic.

64 Samples Per Pixel, 5.839 seconds to render. MIS with Power Heuristic. Now with fresnel reflections!

64 Samples Per Pixel, 5.899 seconds to render. MIS with Power Heuristic.

Heres another update on MIS with some updated probabilities. I think I fixed the weird extra brightness? ~1000spp

Heres another update on MIS with some updated probabilities. Its certainly brighter than it should be, I think. ~600spp

Heres vanilla path tracing -- no MIS, just ~2750 samples using only paths

Its not perfect. But heres 64spp with MIS. 4.053 seconds to render