1. In an N-point Fast Fourier Transform (FFT) processor of the type having a butterfly operator for performing elemental 2-point transformation defined by the following complex relation EQU P' = P + Q EQU q' = (p - q) .times. w where P and Q are two complex data points spaced from one another by N/2 and W is a complex coefficient in the form ##EQU18## for time domain-to-frequency domain transformation and ##EQU19## for frequency domain-to-time domain transformation, ##EQU20## and an FFT memory for storing the new set of N complex data points P' and Q', said butterfly operator performing N/2 elemental two-point transformation to achieve a pass during which a new set of N complex data points are generated, said FFT processor performing log.sub.2 N passes to achieve an output array of complex data points, the improvement characterized in that said butterfly operator comprises: first computing means for computing P'; first storage means for storing P' in said FFT memory; second computing means for computing Q'; second storage means for storing Q' in said FFT memory, and control means for controlling the sequence of operation at said first and second computing means and said first and second storage means so that said first and second computing means begin computing a present pair of points P' and Q' substantially simultaneously and said first computing means finishes first, said first storage means storing the present P' in said FFT memory, and said first and second computing means beginning computation of a new set of points P' and Q' while said second computing means finishes computation of the present Q'.