so apparently google have added a little bit of JS to youtube that adds a delay for loading, but only if your useragent is Firefox.
old.reddit.com/r/firefox/comments/17ywbjj/whenever_i_open_a_youtube_video_in_a_new_tab_its/k9w3ei4/?context=4
you can fix it by adding this line to your uBlock Origin filters.
www.youtube.com##+js(nano-stb, resolve(1), *, 0.001)
UPDATE: They fucking admitted it! Out loud!!
plush.city/@PsyChuan/111450300782038659
