[TomGuy]

Something has been happening with Firefox that has me puzzled however. It devours memory

That is a problem FF engineers seem incapable of resolving. It has been a consistent problem since about version 0.07. It was monstrous under 2. Somewhat better under 3.

FF blames it on add-ons. But, add-ons aren't the problem. FF fails to release memory whenever a webpage is closed. A high-graphics or flash video or other video webpage consumes allot of memory and retains it, even after the webpage is closed.

I typically have to shut FF once or twice a day to release the memory.

[AFreeBird]

You might also want to try clearing cache.