1. For internal drives, if it is SATA II, then its ok.
2. For USB HDD, it should be @ 50mb/s. Is your usb hdd is too old or you didnt plug another usb jack for auxiliary power?
3. Sometimes flash drive get slow when its old and reduce speed.
If you think its happen from any sudden action, then you can give a clean installation of os. Mobo USB port never do this slow. I use 7 years old mobo which is still faster as before. Love my gigabyte mobo.
Did you check from new account? You can at least try.