One of the controversial changes to this version is the removal of the option to disable Javascript, which is now enabled by default and provides no option to disable it, without using about:config. I think I wrote a mention of this back when the change was first made public in some early alphas for version 23.
One odd thing that I have noticed with 22 is that if I have the browser open for a while 5 or 6 hours of surfing etc, my system memory shows more and more used over time to around 1.4GB even if browser tabs have been closed etc. If I close FF and re-open it, it goes back to Windows 7 32-bit running on 750MB idle and 850MB of 3GB RAM with browser open clean to home page of google. Not sure if the memory consumption is a leak or a temp cache in RAM that gets dumped when the browser is closed and reopened.
This is not 22-specific and has been a massive issue with Firefox pretty much since it was released. As far as I understand it it actually stems from their use of a conservative Garbage Collector framework in C++. I could go into numerous technical details but the jist of it is that Garbage Collection has been shown to be unreliable in languages like C++- the Garbage Collector has to be conservative because if it was to cleanup a object that was referenced the program would crash, so if in doubt it let's it sit around. having more add-ons seems to cause more problems; and based on about:memory after having a large working set in FF a lot of the "leaks" appear to be in the Javascript interpreter.
At the bottom of the list for many versions is "Miscellaneous memory safety hazards" with versions appended to them and it appears that even in FF 23 there are some still outstanding to be labeled as critical.
That is a list of fixed issues.
