what model USB 16GB flash drive did you buy?
a friend of mine bought a kingston 32GB USB 3.0 and it is slow as **** maxing out at 10-15MB/s in write,
the read speed were a bit better.
I got a Corsair Survivor 16GB USB 3.0
it works flawlessly, max 40MB/s in write and max 80/85 read
😉so it all comes down to, have you bought a crappy USB 3.0 flash drive?
and does the folder you're copying filled with a bunch of small files? try to copy one large file to see 'the speed'
rig: Impact VII / 4790K / Crucial Ballistix SP 16GB 1600Mhz/ 256GB 850 Pro
Corsair AX760 / H105 AIO Watercooling / Bitfenix Prodigy
laptop: G75VW 3630QM / 670m /16GB RAM / 256GB 840 Pro + 750gb/ BD drive
Gaming OC for 670m 750/1750