There are sparks and fuses. When you stop moving in your current cut path, a fuse would start going up from the base of your current line, it would freeze when you resume drawing. Also, after a certain time the sparks turn into supersparks that can also climb the current line.
The fuses are too wimpy, and practically speaking, you will not find yourself idling in this game much.
The super sparks, on the other hand, i feel are bending the fairness of the game. QIX comes from penny arcade, and this guy, while still on the gentle side, was shaking you like a nice, fat bully - QUARTER IN - MINUTE OUT - NOW BEAT IT!