Your power estimates are off by a factor of ~10 with current technology. Current DGX workstation deliver a much higher speedup for ray scene intersection than 3

Your power estimates are off by a factor of ~10 with current technology. Current DGX workstation deliver a much higher speedup for ray scene intersection than 3x. MLT is not used for animations because it is temporally unstable in a perceptually unfavorable way: the artifacts are more blotchy than noise while the human vision is more tolerant to noise. Recent developments around temporal MLT should mitigate that, but these require you to render multiple frames simultaneously. Thisnmakes them unsuitable for real time applications. Also, the thing about MLT/bidirectional/unidirectional pathtracing is that there is no universally best method. All of then have weaknesses. There are examples where each method is worse than the others in an equal time comparison. The best performance improvements that you can get with any of these Monte Carlo methods are always based on improved strategies for drawing the samples (importance sampling, QMC). Incorporating non-local information for local importance sampling will be the next big thing. As for color noise: it is an undesirable artefact, but if you importance sample the spectral color response curves for the human eye (or your display device) correctly, then the spectral noise vanishes at least as fast as the other sources of noise in your scene.