The growth in browser-based computations is raising the need for efficient local storage for browser-based applications. A standard approach to control how such applications access and manipulate the underlying platform resources, is to run in-browser applications in a sandbox environment. Sandboxing works by static code analysis and system call interception, and as a result, the performance of browser applications making frequent I/O calls can be severely impacted. To address this, we explore the utility of next generation non-volatile memories (NVM) in client platforms. By using NVM as virtual memory, and integrating NVM support for browser applications with byte-addressable I/O interfaces, our approach shows up to 3.5x reduction in sandboxing cost and around 3x reduction in serialization overheads for browser-based applications, and improved application performance.