Relative energy drift (lower panel) and dispersion (upper panel) vs. initial energy of stars after an impulsive perturbation for four different initial angular momentum bins. Crosses are for J/J_c values between 0 and 0.25, triangles for values between 0.25 and 0.5, diamonds for values between 0.5 and 0.75, and squares for values between 0.75 and 1 (J_c is the maximum allowed angular momentum for a given energy). Data points show the energy changes at the end of the simulation. Solid lines are the analytical expectations (Eqs. (6) and (9)). The initial energy in the abscissa is normalized to the binding energy of the cluster, E_bind. Error bars for the simulation results are shown separately from the data points for the sake of clarity.