This sounds great, but if all you're going is sending an AJAX request in the worker and stuffing the response into some element, I don't see much benefit. Most of the time you use an event handler to deal with the response so you're not blocking the main thread anyway. However, if there is any computation, DOM walking, or markup generation, I would definitely use a worker for that.<p>Unfortunately, this doesn't help the 60% of my users who really need it: the IE users with slow JS engines. I've measured 1-2 order of magnitude differences in performance between IE and Firefox/Chrome/Safari in my codebase, and there's just not much I can do for the IE users without withdrawing functionality I'm required to give them. (I wish Chrome Frame was an option, but I suspect that if they had the ability to use that, they'd have the ability to change browsers too, and they don't.)