I closed all tabs but this one, https://support.mozilla.com/en-US/questions/794907 , killed firefox4, restarted and chose "restore". it loaded up to 128.5Mb. After I started typing it went up to 130.5. Now 131,122, and I stop typing. Then it crept crept up to 134,468, and stayed there for a minute while I did nothing. When I started typing again, it started creeping up. When gmail is open, it seems to creep up faster. Surely it's to do with scripting? But yup, it keeps going up and up... I liked firefox 3 for it's low memory footprint (compared to IE and chrome), but FF4 has a problem. It's now at 151,966 - this is the only tab open and all I've done is type this. Now it's 154, 492. Could it be something to do with the string allocations for text typing? I opened a View Source window, and looked at that, and when returning to this, memory had gone back down to 133Mb. It's now up to 139,308, and increasing again. While I'm typing, processor usage goes also up to 20-30% (from 0-1%)

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Now, let's try again. I have Javascript disabled in the options. Started firefox (home page about:blank) and loaded up this page. Memory went up to 120,808. It's still there now, fluctuating between that and 121736. Peak usage is 127636. It's not really going up any more than that though. Perhaps the answer can be found in whatever the scripts are doing on this page when the user is typing. It's still at 120828, so there is apparently no creeping memory usage on this page where there was with JS enabled. Hope this info is of use.

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