@AMCarter - yes, the "spinning wheel" is what I described as "cursor wait" - totally annoying and clearly still a memory issue. Its essentially still a freeze, since you cannot do anything while it happens. Something like this normally only happens in programs when you do something very heavy, eg. when I open a very large file in Photoshop. Its certainly not normal for a browser to be doing continually, which Firefox does.

I am happy for you that it is somewhat better on Mac (you did not indicate how long its been running or how many tabs/windows you have open).

Have you noticed any issues with scrolling web pages? Jerky movement or just nothing happens?

If anyone really does have a problem it is best to start your own tread, but please then be prepared to give full details and to try with add-ons and plugins disabled (unless a specific third party application is the cause. )

Listen, we have been hearing the SAME THING FOR YEARS. There is absolutely NO NEED for any new threads whatsoever. What is needed if for the Firefox developers to sit up, take notice, put their self pride aside AND FIX THE PROBLEM ONCE AND FOR ALL (not yelling, its emphasis). The problem is Firefox, not add-ons or extensions.... its just the same with none of these.

Lightning Jack, I'm going to lock this thread as it's turning into "Me Too" thread. However I want to point a few things out:

1. Mozilla has a dedicated team of developers who's only job is to reduce memory usage in Firefox. They have been working on this for about a year or more. They have accomplished ALOT, from reducing the memory Firefox uses in Javascript, to reducing the memory add-ons can leak, to better reporting tools, fixing memory leaks, etc. You can read about the team at https://wiki.mozilla.org/Performance/MemShrink. Their work has been showing up in several Firefox versions, most recently 15.
2. Have you tried creating a new profile and testing the memory usage there (don't look in task manager, go to about:memory)? and while we are on the topic, go to about:memory and hit "minimize memory usage".
3. If you have a SPECIFIC memory usage problem that you can reproduce, then feel free to file a bug at bugzilla.mozilla.org. Don't do that though for general "Firefox uses too much memory" or "with 5 tabs open Firefox uses too much memory". Bugzilla is for specific bugs that can actually be fixed.