I don't get the point. The only time a blank tab opens is when you're typing in a URL or search phrase, at which point your eyes are on the chrome anyway. If the Cognitive Shield has any perceptible load time, it's not worth it. Granted, at least it doesn't look like an error message like IE7's default blank tab.
The mission is to make it possible to click some easy links without the visual clutter that other browsers' start pages give.
Have you not seen Speed Dial/Chrome/Top Sites? Because this is the exact same functionality as those other ones, and none of them have perceptive load times. Firefox is playing catch-up here: it's not giving anything particularly new.
