Might work, but lousy work is involved Rated 1 out of 5 stars
Pavlov says that RAMBack 1.0 is supposed to work with Firefox 3.0a8pre - 3.7a1pre and that the add-on was last updated November 7th, 2007, which seems a little odd, for Ffx 3 did not exist until quite a while later and he did not provide a date for when he said it'd work for these Ffx versions.
However, there's another problem and this one is about usability. While the above oddness should require a brief explanation in the page for installing the addon, there's another problem that's more important and it's about consistency, or rather a lack thereof, with naming conventions.
His description for the addon is, "RAMBack will cause Firefox to issue an internal notification to free up memory that is otherwise held for performance purposes. Additional items will be hooked into this notification in the future" and further down a little in the install page he says that it lets "you clear internal Firefox caches".
Memory usually means RAM, which is not disk files, while cache is on disk; usually, anyway.
In the following forum page, holy_saiyan1 says that this addon puts "a "Clear Caches" option under the Tools menu".
This is bad inconsistency; not minor!
Either the addon or the option it adds to the Tools menu is MISNAMED. The two names should match so that people like myself don't damn lose hours trying to figure out how to use the addon, for when I check the addon through the FFx Tools menu, the addon is enabled, but its Options button is disabled, there's nothing said there about the Clear Caches option in the Tools menu really being RAMBack, and I don't find any Tools menu option called RAMBack. So of course I searched to try to figure out this addon, for it was seeming to be rather totally useless; half-disappeared somewhere into the Twilight Zone. That's is until I checked the above Mozillazine forum page for which the link was found with a Web search.
I will grudginly recall this unprofessional misnaming of either the addon or the option it adds to the Tools menu, as well as recalling that it doesn't so much free RAM, as it does eliminating cache, which is on disk; not in RAM. This amounts to cause for a grudge.
But I now know that it's working with my installation of Ffx 3.6.3; yet, if all it does is clear cache, then it evidently is not needed if we also have Click&Clean installed. The latter can be run to clear only cache without needing to close or shut down Ffx and gets a 5* rating average from 17 users; there's a link to the developers' website; it's currently maintained; and it provides considerably more functionality, permitting to clean more than only cache.
I recommend using Click&Clean, instead, and your Ffx browser surely won't complain about discrimination. It won't report you to the ADL.