> I don't know what the fuck's going on with YouTube. The night before last it was > stuttering badly for all videos on my Win7 machine (quad E5 Xeon) but playing fine on > my MBP (four-year-old i7).
Safari, at least on Yosemite, forces YT to the HTML5/h.264 player so QuickTime's hardware decoding comes into play. It's a much nicer experience than the Flash player.