  From information theory and thermodynamic considerations a universal bound on
the relaxation time $\tau$ of a perturbed system is inferred, $\tau \geq
\hbar/\pi T$, where $T$ is the system's temperature. We prove that black holes
comply with the bound; in fact they actually {\it saturate} it. Thus, when
judged by their relaxation properties, black holes are the most extreme objects
in nature, having the maximum relaxation rate which is allowed by quantum
theory.
