- Update with Vista SP1 - The default file copy routine has been reverted back to perform cached file copying by default. Except when a remote file is read or written, then it tells the client-side remote file system driver (Rdbss.sys) not to perform caching, so only the local read or write operation is cached in memory. More Info Mark Russinovich
But apparently the I/O rutines in the system file cache manager are so fast that even if it ruins the file cache, then the cached file copying is quicker. This is probably because the file cache works like a large read ahead buffer. When doing a file copy on the same disk, then it doesn't have to constantly move the hard disk head back and forth between source and destination. Another reason why cached file copying feels quicker is that when the cache manager has read the entire file into memory, then the file copy dialog is closed before it has finished writing to the destination file.
Configure this DWORD registry value to use cached I/O requests when doing file copy:
Note Microsoft have identified several performance issues in Windows Vista, and created several patches that address some of these issues. MS KB938194, MS KB938979, MS KB941649, MS KB941600, MS KB943899 (Will over time be available on Windows Update, and will be part of Vista SP1).
[HKEY_LOCAL_MACHINE \SOFTWARE \Policies \Microsoft \Windows \System]
CopyFileBufferedSynchronousIo = 1 (Default = 0)
More Info MS KB941673 (Hotfix is required)
Related Slow file copy caused by automatic tuning of TCP/IP RWIN