The latest changes done as part of this are only present on Aurora (Firefox alpha) and the feature is turned off by default. Also, I have my Firefox (Aurora ag

The latest changes done as part of this are only present on Aurora (Firefox alpha) and the feature is turned off by default. Also, I have my Firefox (Aurora again) running for over a week now on my dev machine with > 50 tabs open an I have had no issues with memory. I suppose there is some problem with one of your add-ons. Try creating a clean profile and see if it's any different.