I want to thank the Firefox team. The memory leak that made earlier versions of Firefox so frustrating to use has returned in versions 22 and 23. Anyone you keeps multiple tabs open in a Firefox window will discover how the leak hobbles the computer it's on after opening five or so tabs. Closing Firefox and reopening doesn't work to free the memory - the only solution is a reboot.
I was feeling so un-frustrated and was having a trouble free computing experience without the leak that I didn't know what to do. Fortunately the FF team have relieved me of these issues - thanks!
PS: I cannot seem to provide feedback at https://input.mozilla.org/en-US/ - I can't log in.