Simulation of the pantograph–catenary dynamic interaction has now become a useful tool for designing and optimizing the system. In order to perform accurate simulations, including system non-linearities, the Finite Element Method is commonly employed combined with a time integration scheme, even though the computational time required may be longer than with the use of other simpler approaches. In this paper we propose a two-stage methodology (Offline/Online) which notably reduces the computational cost without any loss in accuracy and makes it possible to successfully carry out very efficient optimizations or even Hardware in the Loop simulations with real-time requirements. •A Finite Element model of the railway catenary, based on the Absolute Nodal Coordinates Formulation, is presented.•The classical time integration approach is reviewed under a linearized formulation.•A new two-stage strategy (Offline/Online) is proposed to make highly efficient dynamic simulations.•Computational cost reduction is highlighted, achieving real-time response for many catenary models.