Once upon a time I was running a nightly backup program that copied files from the internal SSD of a Windows machine to a LAN-resident NAS with a mechanical hard drive. The backup job would take from 36 to 45 minutes to complete.

Then, I changed the backup destination to an external SSD (a Samsung T5 formatted with NTFS) plugged into a USB port of the Windows machine (not sure if the USB port is version 2 or 3). Now, the backup takes 1 - 2 minutes.

This is a replication type backup, the software compares a folder on the Windows machine with a copy of the folder on the external device. Any new or updated files are copied from the Windows machine to the external device. The folder being backed up is about 30GB with about 87,000 files in it.

Not sure exactly what accounted for the speed increase. It could be, not having to deal with Ethernet traffic on the LAN though there are not many devices on the LAN. It could be not having to deal with a mechanical hard drive. Or, maybe the NAS itself was a bottleneck. Or, a combination.

I still make daily incremental and periodic full backups to the NAS. And, I sleep better because of it. Two different types of backup made to two different types of hardware. They don't teach that in nerd school :-)