[dear]

In my case, everytime I open a new tab, the mem usage goes up. But when I close a tab, it does not necessarily go down, or just goes down a little. So the overall trend is it goes up, until it can no longer function (freezed up on my old 4G computer). Then I have to kill and restart it.

I use OSX's Activity Monitor to see the mem usage.

[mikeratcliffe]

Can you try running in Firefox's safe mode and let us know if you have the same issue... sound to me like one of your extensions is leaking.

[FreeFull]

This isn't something that happens to all users. Ever since Firefox 4, I've been able to open literally hundreds (400 to 600) tabs without suffering much of a hit at all. This is on Linux, and with several addons.