Early evaluation allows to execute operations when enough information at the inputs has been received to determine the value at the outputs. Systems that can tolerate variable-latency units, such as latency-insensitive or asynchronous systems, can enhance their performance by using early evaluation. The most relevant example of a unit with early evaluation is the multiplexor: the output can be determined as soon as the information of the selected channel arrives, without waiting for the other channels. This paper analyzes the potential impact of early evaluation in concurrent systems. An analytical model, based on a Petri net extension with early firing is proposed to estimate the performance. The reduction of the analytical model to a linear programming formulation for an efficient estimation of the upper bound for the system throughput is proposed. The results show the accuracy of the model and the benefits of early evaluation.