blog.mozilla.orgFirefox 15 prevents most memory leaks caused by add-ons, including Firebug. For many users with add-ons installed this will significantly reduce Firefox’s memory consumption, without requiring upgrades to those add-ons.
blog.mozilla.orgFirefox 15 prevents most memory leaks caused by add-ons, including Firebug. For many users with add-ons installed this will significantly reduce Firefox’s memory consumption, without requiring upgrades to those add-ons.

Hmm, FF13 did limit memory use to 50% on my 8GB system, FF12 would continue gobbling it up till the system became unresponsive.
And FF14 is back to where FF12 was...
This is by saving a lot of photo's and documents via right-click.