Identity Safe causes Firefox to consume large amounts of memory when active. After several hours of casual browsing, Firefox would gradually take over 500MB of RAM on my computer when Identity Safe was on, regardless of whether I even used the feature. Firefox also refused to release that memory even when I close all but one tab, and load a blank page in that tab. I did some rough testing to confirm that this problem is caused by Identity Safe and not Firefox or any browser extension.
I opened a new instance of Firefox and browsed through all Mini and Inspiron netbook listings from the Dell Outlet website with Identity Safe on, recording Firefox's memory use in the Task Manager after I was done. [ http://www.dell.com/us/en/dfh/notebooks/ct.aspx?refid=notebooks&s=dfh&cs=22 ] I then closed Firefox (which cleared private data), turned off Identity Safe, and did the same thing again. Memory use with Identity Safe was around 250MB, while Firefox without Identity Safe used only 150MB of RAM after the test.
I tested again by opening a new instance of Firefox and opened 100 tabs with my Hotmail inbox open in each tab, while Identity Safe was off. I checked the Task Manager and saw Firefox's memory consumption continuously rise while the tabs were loading. When Firefox hit 450MB RAM, I closed all but one tab, navigated to about:blank, and waited a couple of minutes while Firefox gradually released memory. When Firefox stopped releasing memory for a minute, I measured its memory usage, closed it (clearing private data again), turned on Identity Safe, and repeated the test. Firefox's memory use would drop to as low as 120MB without Identity Safe, but refused to drop below 300MB with Identity Safe on.
The Norton software I am using is the Comcast-branded version of Norton Security Suite. I imagine that Norton 360 and possibly Norton Internet Security users might also be experiencing the same issue. My Firefox version is currently 3.6.11, although this problem occurred even before this version, and I am running Windows 7 (64-bit).
Even though these tests aren't scientific or exhaustive, I hope something can be done about this issue. Thanks for your time.