  We study effective relaxation time of viscous hydrodynamics of strongly
coupled non-conformal gauge theory plasma using gauge theory/string theory
correspondence. We compute leading corrections to the conformal plasma
relaxation time from the relevant deformations due to dim-2 and dim-3
operators. We discuss in details the relaxation time tau_eff of N=2^* plasma.
For a certain choice of masses this theory undergoes a phase transition with
divergent specific heat c_V ~ |1-T_c/T|^(-1/2). Although the bulk viscosity
remains finite all the way to the critical temperature, we find that tau_eff
diverges near the critical point as tau_eff ~ |1-T_c/T|^(-1/2).
