Firefox 11 32 bit or FF 9 , OS Win 7 Ultimate 64 bit FF Addon Memory fox reduces memory usage of Firefox 11.0 or earlier considerably. For me and others (see reviews) it drops memory usage usually by 60- 70%. http://www.browsermemory.com/ https://addons.mozilla.org/en-US/firefox/addon/memory-fox/ Ever since I installed Webroot ( yesterday) am getting memory release failure on afom.exe - which is the memory fox executable. Disabling Webroot causes Memory Fox to work properly with no errors or Memory release failures. Excerpt for first link (browsermemory.com) below: During the early development phase for Memory Fox I've discovered some API calls internally within the core of Firefox that would habitually cause an increase for the two types of memories, Virtual Paging and Physical Ram. I initially tried utilizing the coding within an XPCOM DLL to force a flushing of the Ram memory back to the Virtual Paging thereby having Firefox close some of the orphaned files and memory handles. This message action allowed me to post out to the Firefox.exe some additional API messages to halt this redundant action causing the increase. What a user would see is the Ram Memory being again filled in by the Virtual Paging Manager, and this being ONLY the valid and essential pages of information need at that current immediate time. This action would be without the inclusion of unnecessary obsolete data paging information that had been left abandon in Physical Ram. This operation action would seem to improve memory intermittently at times, so I moved the code out of the XPCOM add-on to an Out-Of-Process application as a stand-alone known as Memory Fox. Memory Fox would reduced the overhead of the Physical Ram which would indicate that it was successful by testing with the same Tabs Opened ( With ) and ( Without ) the aid of the Memory Fox add-on as being activated. Although, one could verify that there would be a normal increase in the Virtual Page memory, the idea was to increase as much as possible the available Physical Ram memory. The action would lessening the chances of a memory exception failure by providing a longer usage time for the Firefox browser session or allow other applications running parallel the same advantage. Recently, in a new beta version of Memory Fox, I've injected a DLL to remove the offending API calls before they are consumed by supporting functions internal to the core Firefox code.