Just found all my friend MacBook Pro 2016 and 2017 including myself have a huge delay when you swipe backward pages at YouTube when watch last 4 video at the bottom last search result. When without scrolling down the page with click the video and after loading then swipe backward pages will have a delay before reload back where you are. Funny thing is the top video in search result doesn't have any delay. Only those bottom 4 to 6 video is affected. Suspected something wrong JavaScript.