Jetstream is [only] a javascript benchmark suite - according to the site. What do you think about that limitation to judge the quality of browsers?
What were your "seat of the pants" impressions? If you were to go by Jetstream alone, Firefox should be the best performer. Firefox is fairly quick on my machine out of the box, until you add a few extensions. Then it starts to lag rather quickly, and tabs either freezing, or slow to switch, is a constant issue for me. And it seems that multi-process isn't anywhere close to ready for primetime.