I would not qualify this camera as blazing fast.....fast is my 5D MKIII with the 70-200. Using the X-E1 is like using the older model canons with a Sigma lens, it hunts quite a bit. But robinchee's advise about enlarging the focus area should be worth trying.
Actually i'm quite curious. under what kind of situations will it start to hunt? Cos usually when I half-depress the button, the beep sound comes on almost instantly, with the green box.