Impairment under delayed auditory feedback (DAF) has been reported in tasks such as speech, tapping, and music performance, with qualitatitively similar impairment in each. One characteristic of the DAF effect in adult speech is maximal impairment at a delay near 200 ms (the ``critical interval"), with less impairment occurring at shorter or longer delays. There are, however, conflicting data about whether or not this critical interval is affected by performance rate. The current research investigated rhythmic tapping under DAF, and unequivocally established that the critical interval in this task is affected by tapping rate, with a longer delay causing maximal impairment at slower tapping rates. These results are compared with the data reported for speech, and discussed from the perspectives of feedback control, entrainment, and Mackay's (1987) Node Structure Theory.