  We compute the hydrodynamic relaxation times $\tau_\pi$ and $\tau_j$ for hot
QCD at next-to-leading order in the coupling with kinetic theory. We show that
certain dimensionless ratios of second-order to first-order transport
coefficients obey bounds which apply whenever a kinetic theory description is
possible; the computed values lie somewhat above these bounds. Strongly coupled
theories with holographic duals strongly violate these bounds, highlighting
their distance from a quasiparticle description.
