Can you check how your system behaves when you do:
echo 1 | sudo tee /proc/sys/vm/dirty_ratio
I had really slow USB transfer speeds (only to pen drives, not to USB disks), and this "fixed" it for me.
(Actually it only cures a symptom, because the default value of 10% dirty cache should work just as well.)
Maybe this can help determine the underlying problem.
Can you check how your system behaves when you do:
echo 1 | sudo tee /proc/sys/ vm/dirty_ ratio
I had really slow USB transfer speeds (only to pen drives, not to USB disks), and this "fixed" it for me.
(Actually it only cures a symptom, because the default value of 10% dirty cache should work just as well.)
Maybe this can help determine the underlying problem.