iPhone/iPad only: Backing up my photos is not instantaneous and can take several minutes/hours, even for a single photo.

Check in the settings of the application, menu “automatic loading”, that the backup is activated, in wifi and 4G if necessary. If the backup is only scheduled for wifi networks, then this may explain the slowness because nothing happens until you are under wifi coverage.

If the backup is interrupted see the article « Application Hubside Drive iOS: La sauvegarde est interrompue. »