I have a gaming laptop and a phone, both of which have USB 3.2 Gen 2 and Gen 1 ports. I also use a USB 4 Type-C cable. Now, recently, I have downloaded music files of over 300GB. If I transfer them one by one, it takes a lot of time. Today, I compressed the folder to a single zip file, and the transfer finished in less than 20m. Why is that so?
No, is not the phone’s CPU. I guarantee you that can process several gigabytes a second.
It’s the overhead of all that handshaking and confirmation coming over USB, and having to be verified with the sometimes slow phone storage chips or worse on a microSD.
It’s IO overhead and waiting all over the place, not a CPU bottleneck.
Why does this overhead not exist when I’m sending files over USB to an external HDD or flash drive?
I have an external HDD array connected via USB 3.2 and it handles file transfers same as a SATA drive. There’s no handshaking beyond the initial negotiation of the USB connection, certainly not on a per-file basis.
That’s using eSATA for a protocol and not USB in all likelihood. Also a lot of the handshaking and confirmation come from the USB driver itself. You won’t see anything fancy, it’ll just be annoyingly slow.