The effect of signal decorrelation on the performance of the Butterfly Search velocity estimator is examined. An analytical approximation for the expected value of the Butterfly Search L(v) function is developed for three cases of interest. The approximations are verified against synthesized echo data. It is found that the peak value of the L(v) function is limited by the rate of signal decorrelation. The results show that improved performance may be obtained by processing and averaging subsets of echo ensembles, rather than applying the Butterfly Search to the entire ensemble simultaneously. For lower SNRs, processing the entire ensemble at once produces equivalent or better results than subset processing. Results from echo data obtained in-vitro are presented which confirm the simulations.