  We analyze the properties of a class of improved lattice topological charge
density operators, constructed by a smearing-like procedure. By optimizing the
choice of the parameters introduced in their definition, we find operators
having (i) a much better statistical behavior as estimators of the topological
charge density on the lattice, i.e. much less noisy; (ii) a multiplicative
renormalization much closer to one; (iii) a large suppression of the
perturbative tail in the corresponding lattice topological susceptibility.
