Procrastination is the avoidance of a particular emotion associated with a task. It could be boredom, frustration, fear or dread, shame or guilt. The avoidance of the task, though, does not mean an avoidance of that emotion, but it's prolongation. You are essentially carrying around that emotion with you all the time. Completing the task, then, is a release from that emotion, not its prolongation.
So there must be some positive benefit to procrastination: one could become habituated to that tension and release of emotion, or thrive on the adrenaline of almost missing deadlines.
Procrastination creates inefficiency, with greater wait times before work is begun. You are "at work" for longer than you are working.
Imagine two people given an identical task. One does it first thing in the morning, and then is released for the rest of the day. The other does not things all day, and finally gets around to the task at the end, but does not experience that early release from the task, and must always keep it in the back of the mind somehow.