This depends on the amount of data and the speed of your Internet connection. Large amounts of data does take time to transfer. The first time you run a backup, all files need to be uploaded in full. This can take hours, and even days, depending on the total size of your data. After the initial backup, only new files and changes to your existing files need to be backed up, which results in much smaller amounts of data that needs to be transferred. After the initial full backup, backup takes minutes or a few hours.