  We performed a comparison of three different numerical codes for constructing
equilibrium models; (I) a code for static equilibrium configurations, (II) an
implementation of the Hartle--Thorne slow-rotation approximation, (III) a
numerical solution of the full Einstein equations by \texttt{LORENE}. We aimed
to construct sequences of uniformly rotating configurations at various rotation
frequencies up to the Keplerian frequency for a hybrid hadronic--quark matter
EOS where a smooth transition is provided between two separate phases. We
investigated the difference of between the results computed by the
implementation of Hartle--Thorne slow-rotation approximation and by
\texttt{LORENE/nrotstar}, respectively. We have conclude that the codes can the
difference between the slow rotating and the fast-rotating approach increase
exponentially, reaching 6.67% for the maximal mass configuration rotating at
the Keplerian frequency.
