system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why copying 1x4000MB file is much faster than copying 4000x1MB file?
gpt
Imagine you are sending out presents to a friend.
Two options: 
1: Make a giant box and throw everything in. Wrap it in gift paper.
2: Individually wrap each present.

Option one is faster because you spend less time wrapping the gifts. The work required to wrap the gifts is called “overhead”.

Back to computers.
The transfer of files has the same overhead, consisting of, but not limited to:
- access times on the reading and writing target
- lookup of metadata to be transferred 
- interruptions on the transfer bus

Hope this breaks it down for you 😊