Smooth does not mean slow, and that depends mostly on the car, next GP take a close look at the onboard camera's and compare Vettel's car to the rest, especially the Ferrari, you will notice that Vettel barely has to make any corrections on the RB while negotiating the turns, its just planted with all the downforce and its effortless to drive, while the Ferrari needs a lot more input and corrections constantly to drive it at the max. While the RB looks the smoothest, it doesn't mean that its being driven slowly as we can see from the lap times.
Just look at the consistantly huge difference in race pace and qualifying laps between Massa and Alonso, and you can see how much Alonso is making do with the Ferrari's ill performance. If it weren't for Alonso, Ferrari would be fighting in between the the Renaults and Williams, and they know that too well at Ferrari, hence they extending his contract just recently.
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