  We construct self-consistent equilibrium sequences of general relativistic,
rotating neutron star models. Special emphasis in put on the determination of
the maximum rotation frequency of such objects. Recently proposed models for
the equation of state of neutron star matter are employed, which are derived by
describing the hadronic phase within the many-body Brueckner--Bethe--Goldstone
formalism, and the quark matter phase within the MIT bag model using a density
dependent bag constant. We find that the rotational frequencies of neutron
stars with deconfined quark phases in their cores rival those of absolutely
stable, self-bound strange quark matter stars. This finding is of central
importance for the interpretation of extremely rapidly rotating pulsars, which
are the targets of present pulsar surveys.
