This, along with the speed improvements (both the UI and content processes) in Firefox 55 have made it my default browser for the first time since Chrome was released.
Open your google/twitter/whatever accounts in separate profiles, et you get the benefits of being "always logged in" with no tracking on your main session.
Having multiple github accounts next to each others is a bliss and prevent so many stupid mistakes I used to make, like commenting with the wrong identity on a PR.
Combined with the tab group extension, it makes currently Firefox the most productive browser experience I had in years.
_well_ what about web sites that use information about your browser that isn't stored in cookies? Check out https://panopticlick.eff.org/
Unless Firefox has a story to prevent this kind of tracking, don't rely on multiple profiles for any important separation you're trying to keep.
Alternatively type "about:profiles" into the URL-bar, which you can also bookmark.
firefox -no-remote -p
If you're not on Windows, you can also instead use `firefox -new-instance -P`, which is better, because -no-remote cuts off communication from other applications to that Firefox instance, meaning that you can't open links from those other applications inside a Firefox instance that's been started with -no-remote.
The aforementioned "about:profiles" also has a button "Launch profile in new browser", which is much easier than the above methods, but those are useful, if you for example want desktop shortcut for your individual profiles.
It sooo much easier when reading articles to be able to zoom in to the 'article text only' in Safari/Chromium.
Despite their claims for it: "Maybe you want to keep your bank’s website farther away from your Pinterest board"
Just be mindful of what add-ons you install.
I have separate LastPass accounts on each chrome profile (one for work and for personal use) and there's no way to keep them separate like this