Thought I would give the latest version a go. Number 57, like Heinz.
They have a portable version, which I think is the same thing.
Does seem to be a fair bit speedier and they claim it uses 30% less memory than Chrome. Still double, at 133MB compared to my old version of SeaMonkey (ver. 2.46).
I was always a fan of Firefox, mainly because of the add-ons, but it did get slow and heavy in the end. Time will tell if it can recover its position and prove to be a good product again.