Yup, speed is everything, all right. Especially when almost all of the instances are less than a second apart. Many are even withing a half second of each other.
I just finished a few of my own (very unscientific) tests, and in all but Adobe and 163, the pages was loaded before I got my mouse from the address bar to the scroller.
Granted, my system isn't exactly "low-end," but it isn't new, either. It is almost three years old, and was fairly high-end when I built it.
Still, looking only at the times MS has, I don't get why they are trumpeting differences that are negligible, at best.
No, wait, let me correct myself.
Looking only at the times that these speed tests that companies are so fond of put out, I don't get why ANYBODY bothers to trumpet differences that are negligible, at best.
Sadly, the lay-man will likely look at these numbers and think they actually mean something.
Anyway, if speed is desired, go with Opera. If Opera were open-source and had viable StumbleUpon support, it would be the perfect browser.