This post on IE9's reliability, show how the IE team engineered IE9's hang resistance so that an unresponsive tab no longer affects the rest of the browser, similar to how IE is resistant to a crashing tab with Tab Isolation.
"We highlight new user experiences that help you recover from hangs caused by Web pages, long- running scripts or slow add-ons so that you can browse continuously without interruption. We also perform a competitive analysis of IE9's hang resistance to other browsers," noted IE team blog.
You can use the Test Drive demo or watch the video below to check out IE9's hang resistance in action.
More Info: Hang Resistance in IE9