Mozilla’s Technical Program Manager Chris Peterson, says that the recent design refresh of YouTube, which uses Google’s polymer technology is causing it to load 5 times slower on Edge and Firefox.

YouTube’s Polymer redesign relies on the deprecated Shadow DOM v0 API that is only available on Chrome, which results in a major difference in UX when they use ChromeYouTube’s Polymer redesign relies on the deprecated Shadow DOM v0 API that is only available on Chrome, which results in a major difference in UX when they use Chrome