Q: Why does a backup/sync using FTP take longer than when I use my FTP client?
When using FTP with SyncBack, the number of calls made to the FTP server are considerably more than when simply copying via a regular FTP client. This is because SyncBack retrieves information on each and every file (last modification date & time, and the file size, for example). This will make the first run much slower as compared to using your FTP client.
Once the first run is complete however, the process in future will be much faster because SyncBack will not need to transfer files that haven't changed.
Note that SyncBackSE and SyncBackPro are considerably faster than SyncBackFree when FTP is used with a capable FTP server, e.g. one that supports MLSD for file listing.
With SyncBackSE and SyncBackPro you can also use a Fast Backup profile to further reduce the backup time.