When writing file content, the file system connector always first writes the content to a temporary file. Currently, this file is always located in the temp directory as specified by the java.io.tmpdir system property. However, if the temp directory is not on the same file system as the target file, then the temporary file cannot be renamed to its final location - it must be copied to its final location and then deleted, doubling the disk I/O for the write.
If we allowed administrators to specify the location of the temporary storage area, they could ensure that it is on the same filesystem as the workspaces used to store content. This would eliminate the double I/O and presumably address the second issue in the attached forum thread.