  We analyze if and to what extent the high energy behaviour of
five-dimensional (5D) gauge theories can be improved by adding certain higher
dimensional operators of "Lifshitz" type, without breaking the ordinary
four-dimensional Lorentz symmetries. We show that the UV behaviour of the
transverse gauge field polarizations can be improved by the Lifshitz operators,
while the longitudinal polarizations get strongly coupled at energies lower
than the ones in ordinary 5D theories, spoiling the usefulness of the
construction in non-abelian gauge theories. We conclude that the improved
behaviour as effective theories of the ordinary 5D models is not only related
to locality and 5D gauge symmetries, but is a special property of the standard
theories defined by the lowest dimensional operators.
