The relative importance of group-velocity dispersion and loss-induced distortion in limiting the performance of optical delay lines based on coupled resonator structures is investigated. It is shown that for the current state of the quality of fabrication both factors play roughly comparable roles for bit rates of 2.5-40 Gbits/s and that as the storage capacity grows, the relative weight of loss-imposed limitation increases. (c) 2006 Optical Society of America.