The periodic orbits of a nonlinear dynamical system provide valuable insigh
t into the topological and metric properties of its chaotic attractors. In
this paper we describe general properties of periodic orbits of dynamical s
ystems with feedback delay. In the case of delayed maps, these properties e
nable us to provide general arguments about the boundedness of the topologi
cal entropy in the high delay limit. As a consequence, all the metric entro
pies can be shown to be bounded in this limit. The general considerations a
re illustrated in the cases of Bernoulli-like and Henon-like delayed maps.