Ive checked out your videos, and yes it might have to do with 3th party scripts. BUT, with some of them enabled, > the problem is gone with Chrome. i agree completely.
This issue now resides in Firefox. Now look, i recorded a gif, with your test page, with all plugins disabled… and in firefox > the problem occurs…
Weird weird, empty page, no extra balast scripts (if those would be the cause), still weird stuttering.
ps. excuse me for my heated previous reply, i was kinda frustraded cause the page is now delayd for going live.
I really appreciate all the help you and the team is putting in to fix this.