These settings, which are hidden deep within Windows XP's System Properties, provide a host of options that allow you to fine-tune the operating system's overall performance and, thus, its interaction with various applications. These options allow you to adjust Windows XP's processor scheduling, memory usage, and virtual memory, as well as its use of visual effects.
You will see details on how the settings in the Performance Options dialog box affect Windows XP's overall performance, and how you can boost performance by changing these settings to suit your system's needs.
Read the full guide here.