With the rapid development of the mobile Internet, users are increasingly accessing Web applications through mobile devices. Browsers provide the runtime support for Web applications, such as computation and rendering. The browser cache supports Web applications to obtain reusable resources directly from the local storage rather than downloading from the network. It not only improves the application loading speed, but also reduces network traffic usage and battery power consumption, ensuring the experience of mobile Web users. In recent years, attentions have been paid by both industry and academy on optimizing the browser cache performance of mobile Web applications. However, most of the existing research work focuses on the overall performance of the browser cache from the network level, and does not fully consider the impact of user access behaviors and application evolution on the performance of the browser cache. To address the issue, this study designs a proactive measurement experiment, which simulates the user access behavior and obtains the resources of the mobile Web applications. Experiment results reveal the huge gap between the ideal and actual performance of the browser cache, and dig out three main root causes to the gap:Resource aliases, heuristic caching strategies, and conservative cache time configuration. Based on the findings, in order to improve the browser cache performance of mobile Web applications, this study also proposes two optimization methods from the application layer and the platform layer, respectively, and implements the corresponding prototype systems. Evaluation results show that the two proposed methods can save the network traffic by 8%~51% and 4%~58% on average, respectively, and the system overhead is small.