The use of ion scattering spectroscopy to study surface properties often requires sophisticated computer simulations of the scattering process. Their feasibility is constrained by the tremendous number of scattering events that contribute to a spectrum. This paper presents a method for minimizing the number of trajectories that must be computed to achieve a given energy and angular resolution in an ion scattering simulation. The method is independent of how ion trajectories are calculated, and can therefore be used with existing simulation algorithms. The method is compared with a Monte Carlo algorithm for a simulation of hyperthermal K+ scattering from Cu(100).