That's a bit ironic. I remember not so long ago I've heard many people who switched to Chrome were deeming Firefox "memory hungry". I haven't heard similar complaints about Chrome up until now.
TreeStyle Tabs is basically my #1 reason why I'm sticking with Firefox.
Tree Style Tabs is, of course, one of the greatest things ever to happen to Firefox. It's on the list immediately after FireBug.
These days, I have been switching over to xmonad (and other simple window managers). Instead of using tabs inside of a browser, I use windows for each page. Next, I have a global key binding (C-o) that brings up windows as I type out tags which I can set with C-j. This way, I don't need tabs anymore, and I don't need impossibly long lists. I can just type the thing I want. C-o mdn, done. C-o google, done. C-o gmail, done. C-o irssi, yep.
I am still trying to figure out if this is better than constantly seeing a list of open tabs.
For browsers, I would need some kind of hierarchy support, though. A bit harder to do in a window manager, but then you'd have it for all kinds of applications. Maybe even combine it with some additional exposed information -- so without support you manager your hierarchy yourself, but if there's an easy way to get a buffer list, the top-level would be from the wm, and the second level from that list.
I would need some kind of display for a browser, though. I'm fine with on-demand buffer lists in editors (and actually turn off sidebars when I use Sublime), but for my browsing habits I'm better off with a list that's always visible.
Firefox's memory usage is a bit less predictable (and can get crazy, especially when you leave badly coded js websites open for days in a row) and there are more situations when you say to yourself "I'm leaking memory, I'd better restart", but Chrome memory usage grows faster when you open more tabs.
Plus, Chrome UI is less suited to many tabs: favicons stop appearing beyond around 30 tabs (for me, it's probably machine-dependent), and the omnibar doesn't give you a way to switch to already open tabs by default.
Plus, Chrome autoupdates aren't exactly optimized for low-end configs.
But even from Chrome's birth, Firefox was already using less memory with lots of tabs.
Firefox uses far less memory per tab, but still chugs down more memory with time. Chrome uses metric shit-tons of memory, but its multi-threading allows individually killing tabs (or just massacring them in bulk if necessary, which it is).
When memory's tight, Firefox seems to bog down as a whole, while Chrome gets boggy on individual pages (and you can kill/reload these as needed).
I find myself using both though I'll fairly routinely go through and kill off Chrome tabs, and periodically restart Firefox, to keep memory management reasonable.
Firefox's tab and state management is far superior to Chrome. Chrome plays better with some advanced sites (notably Google's own webpages, surprise, surprise).
Now I have a 32GB system so it's less of an issue, but Chrome is still seriously a memory hog.
In comparison, I know several people who regularly have more than 500 tabs open in Firefox -- 1200 is the highest number I've heard, though not all of these were loaded at once thanks to Firefox's "Don't load tabs until selected" option.
I'm really curious, why would one do that?