Well, admittedly it is a very short amount of time, (~10ms) but it is in tune with the speed of the engine so it is usable energy. Detonation is the burning of the fuel that occurs over a very short period of time in comparison to 'normal burning'. Instead of the pressures increasing steadily as the piston moves its motion, detonation is pretty much an all at once BANG! It occurs 100 times quicker, in the nanosecond time measure.
Wouldn't 100 times faster than 10 milliseconds be 100 microseconds? That should still be 100,000 times slower than a nanosecond.
Somebody correct me if I'm wrong (I don't like playing with so many zeros.)