Can you check with the users that there aren’t any sync issues in the clients?
I’ve recently seen that if there are issues with files due to wrong file names and the clients are configured to use VFS during the setup phase the clients enter some kind of loop and keep requesting all files over and over. This obviously increases the load on the server immensely.
So make sure that there are no sync issues in the clients.
No, owncloud works with PROPFINDs. Every time any file is changed some special value in the DB is changed for it (I think it is the
etag). This value is then propagated up in the file tree until it hits the root. When the client requests the PROPFIND and compares the
etag of its data with the reqested one, it will start downloading as soon as it receives a new
etag from the server.
For more information read more about WebDAV.
AFAIK VFS doesn’t change anything about this process, only the files aren’t downloaded, there are only “placeholder files” being created (that’s how it works in Linux, in Windows it is using some Windows native VFS API that will create a similar result).