I don't understand how you can be unhappy about the performance of the few last versions of Firefox. It is now quite savy in memory (especially in comparison with Chrome) and handles everything I throw at it without noticeable janks.
The GUI toolkit take its toll but I can't say enough how much the js, html/css renderer, network and memory subsystems have been improved, chrome doesn't feel faster, except on the UI side of things, but can show long lags when loading/rendering. Kudos to Mozilla.
Well it's certainly better. But, as some one who has to run Selenium at work a fair bit (it makes me so sad), I can tell you that Aurora is quite savvy and the memory use never really got out of hand but FF24 still crashes after running a fairly long suite.
unfortunately, our ageing selenium scripts do not work on anything but firefox. Again I want to stress that Aurora works really well on most everything. I personally prefer Firefox to other browsers. But that doesn't mean that FF is perfect... nothing is.
I don't think anobody stated that Firefox is the perfect browser. Each browser has its strenghs and weaknesses but I am more keen to accept flaws on a browser that's opened by nature: that's why I have always been using Firefox, even when in term of performance it was way behind Chrome. Today I am happy that Firefox has caught up and is even doing much better in some area.
I am willing to help you get started, if you are interested.