It depends on what you feel the movement to mean. I used to play it extremely fast, but my view of the movement has since changed. Previously, I saw it as a storm, a whirlwind, not unlike the last movement of 27/2; these days, however, I see it more as a lament and as a song (vocally speaking), in light of which I feel a fast tempo feels rather... stupid. But, tempo in this movement is above all an individual qestion.