Microsoft Knowledge Base Article 278256 contains:

In Microsoft Windows 2000, there are no options to adjust the cache-validation time for either the user or for Kernel mode Encrypting File System (EFS) caches. However, for faster performance, Microsoft Windows XP provides the flexibility to adjust the cache-validation time for both the Kernel and User mode components of EFS. This article provides and describes registry keys that you can use to tune EFS caching.