This paper studies the relative performance of the Coffman-Graham algorithm for scheduling unitary tasks onm processors with unitary communication delays.Using a particular decomposition of CG-schedules, we prove that its worst case relative performance is bounded by $4/3$ for $m = 2$ and that this bound is tight. For $m \geq 3$, we provide an instance of the problem for which the performance ratio is $3 - [6/(m + 1)]$.