You can also have ownCloud scan for manually added files in the background by setting the following in the confg.php file:
/**
* Define how often filesystem changes are detected
* Specifies how often the local filesystem (the ownCloud data/ directory, and
* NFS mounts in data/) is checked for changes made outside ownCloud. This
* does not apply to external storages.
*
* 0 -> Never check the filesystem for outside changes, provides a performance
* increase when it's certain that no changes are made directly to the
* filesystem
*
* 1 -> Check each file or folder at most once per request, recommended for
* general use if outside changes might happen.
*/
'filesystem_check_changes' => 0,