A recent study by Tufts University’s Samuel Sommers concludes that yes, they do–and that the performance boost is shared by both White and Black jurors.
Heterogeneous juries outperformed their homogeneous peers on a variety of different metrics, including time spent deliberating, number of facts considered, number of factual inaccuracies stated, number of stated factual inaccuracies corrected, and willingness to entertain discussion of the possible impact of racism. You can read the study itself here