Despite a steady improvement of computational hardware, results of numerical simulation are still tightly bound to the simulation tool and strategy used, and may substantially vary across available simulation tools or for different settings within the same simulator. Clock- driven simulation strategies proved ef?cient for large and highly active networks but are outperformed with respect to precision by the recently introduced event-driven strategies. Focusing on most commonly used clock-driven and event-driven approaches, in this paper we evaluate to which extent the temporal precision of spiking events impacts on neuronal dynamics of single as well as small networks of IF neurons with plastic synapses. We ?nd that the used strategy can severely alter simulated neural dynamics and, therefore, turns out to be crucial for the interpretation of the result of numerical simulations. Drastic differences were observed in models with spike timing dependent plasticity, arguing that the speed of neuronal simulations should not be the sole criteria for evaluation of the ef?ciency of simulation tools, but must complement an evaluation of their exactness, possibly in disfavour of their speed.