I love and cherish Firefox as a product and a brand, because you have achieved a lot in your past. But now you are failing and it is depressing to see this happen.
As someone mentioned below, Firefox doesn't get due credit when things improve. With Google's massive marketing muscle Chrome ate up a lot of Mozilla marketshare, but to call Firefox failing is completely unfair. If you love and cherish Firefox, contribute to the project. Contributions can be as minimal as being a test pilot.
Have you tried Firefox recently? It beats other browsers in terms of memory use, for example it won both memory usage categories in Lifehacker's recent shootout,
If you do see a memory problem, it might be a specific problem with the addons or plugins you use, please file a bug if so.
Due to a bunch of Chrome bugs in our game I've had to switch to Firefox the last couple of months just to be able to browse other websites. I am amazed at how much they have improved, in terms of memory/speed as well their UI. I've now switched back from Chrome and dare say that I like it better.
As others have said though, the damage was done when so many people tried Chrome. Getting them to even try FF again is going to be very difficult.
Two highly competitive open source browsers is the best scenario the internet has ever had. I just hope we don't screw something up and break the steady state.
"Mozilla needs to focus on making its browser consume less memory and CPU when idle"
MemShrink has been going for a year. Snappy has been going for seven months. Both projects have made big improvements. You really should try a recent version.
Also, http://gs.statcounter.com/ suggests that Firefox's marketshare drop has flattened out and it's starting to grow again.