enigma1 - 9:48 am on Oct 30, 2011 (gmt 0)
Cuz the browser has way more usability and gradually replaces O/S operations and depends what you do. Just the number of sites/logons that I keep active I need 10-15 minutes (over time) to get back to where I was, after I restart it. And it's not the 2 vs 20 active tabs or windows open, that causes the memory problem, just one script is enough to waste the memory.
And as of the noscript is pretty good for casual surfing and does it's job. But if you set temporary exceptions you need to set them again following a restart. When you need to buy something online you gonna need to go over the same process few times with the temporary allow this and that, because of the various redirects to the gateways and noscript refreshes once you flip the active switch. Add to this another 2 extensions (cookies, requestpolicy that have similar options as noscript) and you get the picture of the number of clicks you need to do. It's much worse than rebooting the o/s.
So if FF could properly control memory allocation I would have to restart it only for its updates or for a system reboot.