  We initiate the study of equilibration rates of strongly coupled quark-gluon
plasmas in the absence of conformal symmetry. We primarily consider a
supersymmetric mass deformation within ${\cal N}=2^{*}$ gauge theory and use
holography to compute quasinormal modes of a variety of scalar operators, as
well as the energy-momentum tensor. In each case, the lowest quasinormal
frequency, which provides an approximate upper bound on the thermalization
time, is proportional to temperature, up to a pre-factor with only a mild
temperature dependence. We find similar behaviour in other holographic plasmas,
where the model contains an additional scale beyond the temperature. Hence, our
study suggests that the thermalization time is generically set by the
temperature, irrespective of any other scales, in strongly coupled gauge
theories.
