State estimation of nonlinear stochastic system in the setting of event-based (EB) measurements is quite challenging, because the measurements are not available at each sampling period, but are available only when a certain pre-specified event occurs. Recently, a nonlinear EB state estimator using Sequential Monte-Carlo approach is proposed in [21], where the authors obtained a EB state estimator for a given threshold. In this work, the results of [21] are extended as follows. Firstly, an empirical relation between the EB threshold and the average communication rate is obtained. Then, the performance of the estimator is evaluated by comparing the approximate error covariance matrix with the posterior Cramér-Rao bound. In addition, the computational complexity is addressed using the equivalent flop measure. Finally, the effectiveness of the proposed approach is demonstrated using two simulation examples.