We consider the implications of peculiar-velocity perturbations for the linear evolution of density inhomogeneities in a “tilted” almost-Friedmann universe. Assuming an Einstein-de Sitter background, for simplicity and demonstration purposes, we find that density perturbations grow as \(\delta \propto t\) , as opposed to the familiar \(\delta \propto t^{2/3}\) linear growth. The physical reason is the energy-flux input of the peculiar flows to the relativistic gravitational field, which in turn increases the standard growth-rate of the density inhomogeneities. Hence, linear peculiar-velocity perturbations can mimic, or further enhance, the effects of Cold Dark Matter. Overall, our results suggest that linear structure formation proceeds more efficiently in relativistic tilted cosmologies than in their non-tilted counterparts and/or in Newtonian models. As a result, tilted universes could naturally “form” massive galaxies at higher redshifts, perhaps like those recently reported by the James Webb Space Telescope.