I find that Safari is better/faster with "normal" sites, like say this one, or 99% of the sites I visit. But when I have to visit godawful sites like IGN, Firefox serves me much better. Actually, most video game sites these days have disgustingly bad design. Way too busy, way too fancy, way more complicated than they need to be.
I've been going around a lot of video game sites lately because of all the news from E3, and Firefox is just so much better for the task. Flashblock alone is a lifesaver, since many of these sites have about half a dozen flash items on every page (which makes me want to kill someone...).
But for the sites I actually like to visit, Safari is my #1.