I have been getting this in several sites lately. It's in the status bar at the bottom left of IE9.
In this instance the browser page went white but didn't say it had quit responding, for over 5 minutes. Hitting the refresh button opened the site again.
This happens with almost any site I visit. The site will generally open fine but when navigating through it, the delay happens.
My download speed hasn't fallen off, it's about 11-18Mbs, no proxies in use.
Any ideas would be helpful.