I'm so excited about the future of Firefox. In addition to the above, OpenBSD is currently working on pledge support in FF. In a couple years FF could be simultaneously faster, more private and more secure than Chrome.
I use FF on OpenBSD as my daily browser. I have at least three different profiles running simultaneously with multiple tabs open in each (though I don't go nuts with tabs like some do -- I never tend to have more than 10 or so open).
It does occasionally seem to get stuck in a state where it just starts chewing CPU cycles and RAM. I've seen this mostly with Google sites like gmail or docs, so I assume it's JS-related. But it's fairly rare, and seems to be improving with each release.
The other problem with container tabs, which isn't really a Mozilla problem as much as a Google problem, is that if you have enough segregated google profiles going you seem to hit some google anti-abuse codepaths or aomething. I have 3 separate Google accounts separated with container tabs (on purpose, I know Google supports multiple accounts), and a separate regular browsing container, and occassionally just following a link from Gmail or hangouts where Google bounces you through their redirect hangs for 30 seconds or so. When it's doing that it generally does it consistently though.
I'm so excited about the future of Firefox. In addition to the above, OpenBSD is currently working on pledge support in FF. In a couple years FF could be simultaneously faster, more private and more secure than Chrome.