The main concern of the Internet user-base has shifted from what kind of information are available to how to find the desired information on the Internet thanks to the explosive growth of the WWW and the increasing amount of data available via the Internet. Since mobile agent technology is expected to be a promising technology for information retrieval, there are a number of mobile agent based-information retrieval approaches have been proposed in recent years. For a better understanding and efficiency improvement of these approaches, performance evaluation of great importance. However, most of existing evaluation results are experimental and there is a lack of theoretical performance analysis which is helpful to reveal the insight of the working mechanisms. In this paper, we further the study in [14] in which some primary studies on the performance of several mobile agent-based information retrieval approaches are provided and provide the exact probability distributions of execution time for each approach. Our results reveal the insight of mobile agent-based information retrieval approaches and our analytical method provides a useful tool for further research to information retrieval.