quick as a wink
Also, quick as a bunny or a flash. Very speedily, as in He was out of here quick as a wink, or She answered, quick as a bunny. These similes have largely replaced the earlier quick as lightning, although quick as a flash no doubt alludes to it (also see like greased lightning), and quick as thought, now obsolete. The bunny variant dates from the mid-1800s, the others from the late 1800s.