I can browse this forum all day without closing Firefox. When I look at my statistics from "top" they are consistent and don't seem to show any obvious memory leaks. The same is essentially true of freshports.org, wikpedia.org, wictionary.org, google.com, my own localhost and local area network php development sites, and most of the other sites I use frequently. But if I go to some of the other less well-behaved sites I use every now and then, like facebook.com in particular, then when I check "top" I can see that my memory usage will remain obscenely bloated, even after I've closed the tab, and it won't completely recover until I've closed down Firefox completely and restarted it.