Ap erformance analysis of the conservative parallel simulation protocol is presented in this study. We analyze several performance factors of a simulation model with an arbitrary number of logical processes. The analysis probabilistically identifies the critical path in a conservative model, and it also estimates the number of null messages, which is the major overhead factor of a conservative simulation. Apart from the factors of the hardware platform on which a simulation system is running, null message count is completely based on logical factors such as properties of simulation topology and simulation protocol. Null message count can be estimated in terms of lookahead of logical processes, simulation time, and the connectivity of simulation topology. Several experimental results have been presented to verify the null message count model. Capturing the null message count will lead to a new idea of how to revise the simulation model in order to improve the performance of a conservative parallel simulation.