Re: Fix Thunderbird too!
Unfortunately Mozilla's "fixing" of Firefox has resulted in it using far more memory than before, not less. The usage is spread out over a plethora of separate processes which perhaps makes it less easy to see, but in my testing with my normal set of just over 20 tabs open it uses around double what Pale Moon does in identical circumstances. It's not even perceptibly faster, not that I found Pale Moon slow in the first place.
I agree that it would be lovely to see some real attention to cutting the bloat in Thunderbird, but I'm not holding my breath...