Safari in macOS Big Sur at last supports 4K YouTube playback (i.e. VP9 codec) but still no HDR option such as Chrome has supported for a while now. Looking at CPU/GPU usage we see that 4K HDR in Chrome uses a much more significant amount of resources than 4K SDR does in Safari. Whether this is due to Safari being better optimized than Chrome or HDR being much harder to decode is yet to be deciphered.
