In the era of large-scale surveys, N-body simulations are vital in providing predictions on a cosmological setting. In this talk, I will present details of an algorithm that speeds-up modified gravity calculations (with a particular focus on the nDGP model), to a level comparable with current LCDM simulations, without any appreciable loss in accuracy. Such a speed-up opens up the pathway to modified gravity simulations on the scale of Gpc volumes, with high resolution, preparing these simulations for the generation of mock catalogues for current and upcoming surveys.