That's not a conspiracy theory; it can be explained without assuming nefarious anti-competitive intent. Google has a front-end framework called Polymer, which i

That's not a conspiracy theory; it can be explained without assuming nefarious anti-competitive intent. Google has a front-end framework called Polymer, which it is using to push certain new web standards ("Web Components"). It's also pushing those by implementing them early in Chrome. Since other browsers, Firefox among them, have not yet fully implemented those standards, Polymer reproduces them in Javascript, which is slower than the browser supporting them. A YouTube developer once said on HN that YouTube uses Polymer for non-technical reasons. One could imagine serving as a testbed for Polymer could be that reason, with slower performance on Firefox as an accepted downside.