OK: Epiphany Web browser (webkit based) under Gnome 2.30 on gNewSense is coping with 12 tabs or so and using 170Mb. Tabs include The Verge and other heavy sites. I have javascript enabled. Scrolling is a bit slow on this old laptop. On a 1024 wide screen you get 9 tabs then arrows (i.e. Epiphany does not wrap the tabs bar).

http://thesimplecomputer.info/1-month-with-the-midori-web-br...

Midori has had a facelift (Gnome 3 version). Might be worth a try. Can't install this myself on this laptop without changing the OS.