Super slow USBFlash Performance

GL-MT300N-v2, Sandisk Fit - https://www.amazon.co.uk/Cruzer-Fit-Flash-Drive-SDCZ33-032G-B35/dp/B00812F7O8

Trying to serve some files over SMB. I understand the GL-MT300N-v2 is USB2 but I would still expect at least 10Mb/sec.
Reality is it reads this VFat FS at maybe 500K/sec, while CPU load is 1.0…

What gives? Surely this is a bug somewhere?

500K Byte or 500K bit?

It should be several Mbyte in writing. Can you please try NTFS?

If you don’t remove the USB or power off the router quite often, you can add “async” to the mounting parameters and it could be much faster.