If I recall correctly, NTFS updates a file's access time (or some such) every time anything happens to it, so by default Windows' file I/O is slow. (Antivirus,

If I recall correctly, NTFS updates a file's access time (or some such) every time anything happens to it, so by default Windows' file I/O is slow. (Antivirus, of course, will not be helping that.) Once upon a time you could disable access time updating in the registry, although I assume if you had those kind of permissions you wouldn't be having this problem.