As something of power FF user, I do two key things in Firefox that used to work perfectly, especially with a third thing from Session Manager.

* Multiple profiles simultaneously, one for normal browsing, another for authenticated sites I care about, etc.

* Lots of windows and tabs. My main FF usually had around ~20 windows (spread across a huge virtual desktop) and ~300 tabs.

* The amazing Session Manager addon, which would, when FF imploded, let me restart FF, choose which session to restore, and then do so, perfectly, even restoring windows to their correct positions in sections of the virtual screen several feet to the sides of my monitors.

Like I said, Firefox worked flawlessly for this, while Chrome was a flaming disaster.

The decline in Firefox since has been like this:

1) Session Manager loses the ability to restore off-screen positions.

2) So I switched to using more topic-oriented FF profiles, so that if topic X on virtual screen (2, 3) dies, I can just go restart it on the right virtual screen, without having to move a dozen windows there. Annoying as hell, but not fatal.

3) Firefox has the Great Addon Debacle - where many addons abruptly stop working, including Session Manager.

4) The firefox team recognizes that something like SM is required, but the result has far less time put into it, is buggy, forgets which URL went into some of the tabs, can only restore the last session (so if you restart twice without restoring, rank stupidity follows to restore the session you wanted), and so on.

5) At some point, Firefox starts consuming a LOT more process slots (by default), greatly increasing its ability to consume far, far more CPU time

6) This doesn't affect me a lot at first, since I've long saved process cycles - and power - by suspending all Firefox processes when my screen locks. It's worked perfectly since about a year after JavaScript become a thing (but...)

7) I discover that some aspect of FF, the new, sad, session management, and contention between all the FF content procs now means that when FF awakens after its nap when I unlock the screen, they now want to dump some 2 MB/s of data into my hard drive. After a night of suspension, since FF doesn't realize it was asleep, it apparently walks through every time point where it would have saved and does it all at once. My home and work computers (both of which are pretty meaty) are completely useless for up to 20 minutes after unlocking the screen, as FF hammers the disk drive continuously, often made even worse by FF's ongoing tendency to balloon up to 10 to 20 GiB in each content process.

Obviously I've taken steps to find variables relating to how often it checkpoints, and reduced the frequency. I've cut the number of content proc process it runs, but the fundamental issue is:

For power users with lots of profile and windows/tabs, Firefox used to be The Answer.

Chrome is horrible in the same situations Firefox used to excel in.

I don't want Firefox to become Chrome. Chrome is garbage for us. A browser only suitable for a handful of tabs (i.e. < 100 or so), which will then eat your CPU cores (depending on JS content)

The only thing I wanted was for Firefox to be able to tell me WHICH TAB IS EATING CPU TIME SO I CAN KILL THAT TAB.

Still doesn't do it.

Sigh.

(Arcana: I miss NeWS and "psps" / "pskill" which did address this kind of problem)