Rated 1 out of 5 stars
Well, with that config parameter set to 0 there was still a page (reuters.com) that was badly stalling FF 4 no matter how long I left it unselected while working with other pages. The stall had to do with an auto refresh .js script on rueters.com that is incompetent (fixed by blocking the offensive element with Adblock Plus.).
Using BarTab I was _really_ able to unload the page and eliminate its foul behavior. The tab history problem was a show stopper, however.