Mozilla technical programme manager Chris Peterson stated that Google has deliberately slowed down the performance of YouTube on Mozilla’s Firefox and Microsoft’s Edge web browsers, CNET reported.
“YouTube page load is 5-times slower in Firefox and Edge than in Chrome, because YouTube’s Polymer redesign relies on the deprecated Shadow DOM v0 API only implemented in Chrome,” Peterson said.
“YouTube serves a Shadow DOM polyfill to Firefox and Edge that is, unsurprisingly, slower than Chrome’s native implementation.”
Peterson said that on his laptop, the initial page load takes five seconds with the polyfill – compared to one second without it. Subsequent page navigation performance is comparable, he found.
He suggested the YouTube Classic Firefox extension to restore YouTube’s pre-Polymer design to increase the first-load performance of the site.