Why Do Internet Explorer New Tabs Open So Slowly? (and How Do I Fix It?)
 

In previous posts, we’ve written about the ways we’re making IE9 much faster, like the new script engine that uses multiple cores, and the new rendering subsystem that uses the dedicated graphics chip found on modern PCs. Another aspect of browser performance involves the external code that IE runs on behalf of users, or add-ons.

Add-ons introduce unique features that can enhance the browsing experience. However, they also decrease the browser’s performance in crucial activities like navigating to webpages and creating new tabs. In this way, add-ons affect key usage scenarios like startup and navigation.

Add-on performance is integral to an overall fast browsing experience. IE users expect the browser to be fast, with or without add-ons. We work towards several common goals with add-on developers: providing valuable features with the smallest performance and reliability impact possible (more on reliability in another post).

http://blogs.msdn.com/b/ie/archive/2...rformance.aspx