High CPU usage in Windows 8.1 Pro 64bit When Doing FIle Transfer

Transferring some files from my USB 2.0 External to flash drive USB 2.0 currently, and cpu usage shot up from low 30’s to 73-90 percent in the course of a few minutes here. Seems like Avast bug to me, as when I disabled Avast, the usage went way down

Dropped to 40 percent soon as disabled

Just thought i’d point this out