[CentOS] USB disk IO

Hello - frequently I turn on my external USB 3.0 disk and back. While my
machine is copying and backing up my desktop becomes very sluggish.

Is there a way to change that ? I am using CentOS 7.5 x86 with a very nice
processor extra cores available and plenty of memory. There is no reason
the "other" cores cannot keep the desktop going.

Thanks,

Jerry