  We derive the frequency spectrum of the lowest compressional oscillations of
a 3D harmonically trapped Fermi superfluid in the presence of a vortex lattice,
treated in the diffused vorticity approximation within a hydrodynamic approach.
We consider the general case of a superfluid at T=0 characterized by a
polytropic equation of state ($\sim{n}^\gamma$), which includes both the
Bose-Einstein condensed regime of dimers ($\gamma=1$) and the unitary limit of
infinite scattering length ($\gamma=2/3$). Important limiting cases are
considered, including the centrifugal limit, the isotropic trapping and the
cigar geometry. The conditions required to enter the lowest Landau level and
quantum Hall regimes at unitarity are also discussed.
