  We present a simple derivation of the formula for the Hamiltonian operator(s)
that achieve the fastest possible unitary evolution between given initial and
final states. We discuss how this formula is modified in pseudo-Hermitian
quantum mechanics and provide an explicit expression for the most general
optimal-speed quasi-Hermitian Hamiltonian. Our approach allows for an explicit
description of the metric- (inner product-) dependence of the lower bound on
the travel time and the universality (metric-independence) of the upper bound
on the speed of unitary evolutions.
