Firefox has a known history of being a memory hog – leave it open for long enough with multiple tabs open, and it will slowly drain away your computer’s memory. The so called ‘memory leak’ has always been a problem with Firefox as long as I can remember. Even Mozilla acknowledges the existence of the memory issue and as a workaround it recommends periodic restart of Firefox to bring the browser’s memory usage down to reasonable levels.
But who runs Firefox with one eye on the task manager? Thankfully, an add-on called Memory Restart solves half the problem.
Memory Restart displays Firefox memory usage in the toolbar, and once it gets past an insane level, the button turns red to warn you that Firefox is about to go berserk. You can then save your tabs and restart Firefox to regain all the memory Firefox gobbled.
Alternatively, you can configure Memory Restart to automatically restart Firefox once it exceeds the memory limit. The add-on will automatically save your browsing session and then restore it upon restart. The memory threshold is configurable too.
There is still one issue – compare the reported memory usage of Firefox by the add-on with that by Windows task manager and you will notice that Memory Restart always reports less memory being consumption than the actual figure. I’ve learnt that Memory Restart uses Firefox's about:memory to determine how much memory it’s using, but why the figures doesn’t match, I have no idea.
You just have to allow some margin for this anomaly when you set the threshold, or mentally add 50 MB to 100 MB to the value given by Memory Restart’s icon in the toolbar when you decide whether or not to restart Firefox.