Why do small files take a long time to copy to a flash drive?

Question

USB flash drives

10 GB of small files of 100 kb are copied for about an hour. via USB 3

and one 10 GB file in about 5 minutes.

What could be the reason.

Answer 1

It's a bunch of small files and a flash drive)) this is normal

Answer 2

because with each file the table containing the file structure on the disk is changed and overwritten

Answer 3

It depends on the file system you are using, but if you regularly use this flash drive and transfer so many files, then it is possible that your MFT has grown a lot.
Try this: first copy all the contents to your hard drive, and then either format the flash drive, or even (to be sure) run a write test with a program like R.tester .
It will be enough to overwrite the first 10% of the volume, but you can also do a full test - the graphs are detailed, if there are dips, then you will clearly see them. Then format the flash drive and see if the speed changes.
Also, for copying, try this program, on hard drives it greatly speeds up the process: https://portableapps.com/apps/utilities/fastcopy-p...
Both programs are free and do not require installation.