First of all, what topology are you using? The compensation network has to be designed accordingly.
For good transient response performance, the closed-loop bandwidth has to be as high as possible, with adequate phase margin.
As a general rule, the single-pole (or dominant pole) compensation will result in poor transient response, as the dominant pole will be placed at a low frequency, thus limiting the bandwidth.
For a forward topology in voltage mode you are best off with a two-pole-two-zero compensation.