In the sharp turns, you feel like that's where you should try really hard to go fast. Because you're going so slow!
But really, it makes more sense to slow down MORE, be smooth and controlled and get the turn right. And you'll get a better drive and be faster later. slow in, fast out.
also, the math wins - going 1mph faster on the 1/4-mile straightaway works out better than going 1mph faster on the 100-foot slow turn.