  We explore the impact of dynamical friction on cosmological scales and show
its influence on the evolution of perturbations. In particular, considering
smooth and clustering dark energy models, we describe the role played by
friction by selecting two main hierarchical models, \textit{i.e.}, the first
where the friction term is proportional to the Hubble rate, whereas the second
where friction is induced by the dark energy pressure. The second approach
generalises the first and translates the idea that pressure is a general
relativistic effect, motivating why friction might arise once barotropic dark
energy fluids are considered. The corresponding effects of friction are
investigated at the level of linear and nonlinear perturbations, using the
formalism of the spherical collapse model. Whilst dynamical friction has very
small effects and thus it cannot be excluded \emph{a priori}, dissipative
pressure friction leads to a substantial slow down in the evolution of
perturbations. This can be particularly inferred within the halo mass function,
for which we also employ corrections due to dark energy clustering. To this
end, in order to discern detectable deviations from the standard cosmological
model, we thus highlight where dissipation effects might play a significant
role at large scales.
