This does not seem to be the case however and RAMBack introduced a routine that reduces the memory usage of Firefox 3. Firefox 3 does keep some files in the cache for performance purposes and RAMBack will cause Firefox to issue an internal notification to free up memory.

A commenter on the add-on page said that this add-on “only clears the internet memory cache of sites not currently loaded in the browser” which makes a lot of sense to me. I had troubles finding a way to find out if the add-on is as useful as it sounds.

What I can say is that the memory usage seems to be pretty stable for the same amount of tabs and websites and that it does get reduced by a bit when closing websites. The author of the add-on seems to be heavily involved with the creation of Firefox 3 and it seems that this add-on is really doing what the description says.

Before I forget it. The website of the add-on does not state it explicitly but it seems that the add-on becomes active when the user presses the Clear Caches button in the Tools menu. Would have probably been better if it would automatically do that every x minutes or something instead.

Update:

Before someone says I’m not giving credit. I discovered this add-on in the Delicious Hotlist. Just realized that Lifehacker’s Adam Pash wrote about it as well.