What evidence do you base this on -- your own experience, or that of others, or measurements such as those done by Tom's Hardware, or something else?
I'm not disputing your claim, I'd just like to know :)
http://www.zdnet.com/time-to-take-another-look-at-firefox-70...
http://www.tomshardware.com/reviews/chrome-17-firefox-10-ubu...
googling is not rocket science.
and these three links are only the newest ones, there are more from 2011.
You can even see the bugs that lead to memory regressions there.
Fortunately, although AWSY is useful, it's also a single benchmark with a number of flaws and limitations, and should be viewed accordingly. In particular, it can miss big improvements such as https://bugzilla.mozilla.org/show_bug.cgi?id=695480 and https://bugzilla.mozilla.org/show_bug.cgi?id=689623.
This kind of testing produces results that favour Firefox, because Firefox does very well when you measure memory consumption in a browser session that hasn't been alive for long, but less well in longer-running sessions. This is partly due to its mostly-single-process architecture, which makes for smaller per-tab/site overhead, but fragmentation and leaks hurt more over time.
As a result, at this point in time I find reports from actual users more convincing than measurements done by tech sites. Firefox's memory consumption has improved a lot in the last 18 months, and I've heard lots of users say it uses less memory for them than it used to. I was hoping that antonios might have something similar to say.