Most filesystem drivers for Webdav shares act somewhat like a mirror; if a file is read it's first downloaded then cached in its entirety on a local drive, then read from there. Writing files is similar or even worse- a partial update to a file might involve downloading it first, modifying it, then uploading it again. In many cases that is not optimal. This filesystem driver behaves like a network filesystem. It doesn't cache anything locally, it just sends out partial reads/writes over the network.