I've been staying with Firefox not for the performance (today Chrome loads Google sites like YouTube faster), but mainly for Tree Style Tab extension. I couldn't imagine opening more than a dozen of tabs without it.
I can't imagine having more than a dozen tabs open, period. You tab hoarders will never make sense to me...
For games, I often have a bunch of wiki tabs open at the same time.
Fortunately, I also habituated the simple behavior of "If I realize I have a lot of HN tabs open, right-click and close the entire pane". That's how I know I'm clocking about 100 tabs per two days on HN alone.
Also, Sideberry changed my tab hoarding habit in a way that still results in keeping hundreds of tabs, but using them in much more sensible way. I keep them arranged in trees stemming from topical groups on high-level panels, and trim or kill as they're no longer useful. Most of those tabs are unloaded anyway, but the interface works as excellent short-term (days to weeks, sometimes a few months) bookmarking system - and I don't lose tabs anymore (as in knowing the tab is there somewhere, but not being able to find it in the vast sea of other tabs).
Can't really point to any concrete issue, other than I have a distinct feeling Sideberry is much faster/lighter, and feels more like part of Firefox vs. some bunch of JS faking an UI on top of it. Sorry I can't give you a more objective comparison. I did find this though:
https://old.reddit.com/r/firefox/comments/118ddge/tab_manage...
which is a recent(ish) discussion, and the points made there seem accurate.