https://support.mozilla.org/en-US/questions/1011071

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

Hello big big thanks for your answer... I took time to check everything. There has been some inexpected relaunch (by my mistake). It works now since 32 h. FF was initialy at some 300 Mb... And it is now at 730... I have manged to use my other browsers, and used FF for some 3-4 tabs max.... It is now with 1 only tab... And so much memory !!!!

And of courseI have launched FF in safe mode....

I really don't understand what happens ! Big thanks if you have any clue, or if I can send you anything....

I could not understand much of your message. Did you try Firefox in Safe Mode?

Thanks for your answer... Mine was not not clear... here are just the facts

OSX 10.11.5 FF 46.0.1 lauched in safe mode Initially FF took some 300 MB and after 32 Hours in safe mode, with sometimes 3-4 tabs, and sometimes none, it is now at 730 Mb...

I hope yjses infos are enough and clear... Tell me !

Big big thanks !

I called for more help. Good luck.