A neuromodulation system for use with electrodes to modulate a volume of neural tissue may include a waveform generator and a controller. The waveform generator may be configured to be electrically connected to the electrodes and provide an electrical waveform through at least some of the electrodes to provide a neuromodulation therapy. The controller may be configured to use a program to control the waveform generator to deliver a neuromodulation therapy by delivering both a fast-acting sub-perception neuromodulation and a slow-acting sub-perception neuromodulation. The fast-acting neuromodulation has a wash-in transition period less than a first time duration, and the slow-acting sub-perception neuromodulation has a wash-in transition period more than a second time duration, the second time duration being longer than the first time duration.