There is the problem of web sites too- one popular site generates mountains of of javascript garbage every times you
scroll. See for instance the bug 656347 in the mozilla database.

The site? Slashdot. Mozilla is not happy the way Firefox manages this, but relying on garbage collection
very time you push arrow down is bad.

It has been a turd since this summer, mostly due to the bug in the SQL code which
killed interactive performance. It was repaired this week and should make beta9. It
is also in recent 3.6 builds so mainline firefox is almost unbearable.

Meaningless javascript benchmarks are not very useful for this sort of bug- which
gives 10 second hangs when working with history or bookmarks.

Bug number 595530