Very unusually, everything is working and smooth on Fennec F-Droid for me. Usually it's the opposite but it happens more often these days.
I know you aren't supposed to comment on it, but man, you just never know what will set people off on this site, and god knows they won't tell you. Are people bothered that I chimed in to say "works for me" or that I insinuated Fennec F-Droid is usually less smooth than the Webkit-based mobile browsers? I'll never know for sure. Sometimes with Hacker News, whether a comment is actually well-received feels like a dice roll.
My naive guess is that it's a null hypothesis situation. You not seeing a problem isn't a useful indicator for if there is a problem. More than that, it probably hits too close to home for mostly software devs, with the dreaded "Well it works on my machine."
Must be something like that. More than anything, I'd love to know why Firefox seems to be winning on this page; practically the opposite of what you'd expect out of Google pages (because, even without a tinfoil hat on, it's clear they don't test on Firefox often). Maybe uBlock Origin is just cutting out some poorly-written script, who knows.