restir is more lumen then megalights. but… yes… for any given pixel you gotta limit the amount of lights that are accumulated.
also… emissive materials are expensive cause you hit a surface pixel, detect that it’s emissive and have to gather more data/samples about the surrounding world. means… creating more rays to fire. that’s why emissives are rather expensive or noisy, cause you can’t shoot all the rays. or you’d get the polygon id. and track in which bvh clusters it’s also in and get the spread. this is pretty nuts tho. in the end all you need is the center of the polygon and some ray cones or an approximate probe and hack the spread to look good.