Blackmagic Disk Speed Test
If you're interested in read and write speeds there is an app called Black Blackmagic Disk Speed Test available on the App Store. This doesn't have a database to compare with others but can give you actual speeds for your internal and external drive.
Moving by cut & paste is not really that different from copying and deleting, no.
The explanation for the data loss is buffering. When you ask Finder to cut & paste (or copy and delete - doesn't matter) - all that Finder does it ask the operating system to copy data to the external drive and delete the file from the internal drive.
The operating ...
You are almost there. Check again in Disk Utility app.
You will find APFS as an option in the Format pop-up menu.
You make the same choice of GUID Partition in the other pop-up menu Scheme.
Working as designed. macOS doesn't support the linux filesystems that linux uses to boot. The one I use for booting is ext4.
check what filesystem you formatted flash driver with.
For ext4, you can install one of these drivers.
AJA System Test is another commonly used tool to benchmark disk performance for the Mac. It offers graphs and a text report of performance instead of just a dial indicating transfer speed like Black Magic.
If you want to test random I/O, which neither AJA or Black Magic do, you can use the tool fio like you can on Linux. You can expect the IOPS to be much ...
This could be a few things:
In case you chose to encrypt your backups, it may be FileVault2 is currently encrypting the disk. Here you find some instructions how to check that.
As In the accepted answer, it could be spotlight indexing the disk.
It could be your disk's firmware doing some maintenance task. However, in that case the indicator LED will ...