File transfer speed 115 MB/s
CPU load during transfer %40
Hdd WD my passport 1TB
What filesystem did you use on the WD? If it was BTRFS, you might want to take a look at -> this, and run dmesg to see if your drive is affected. While there are several models and a few different sizes of my passport, the particular 4TB model I have didn't get along with BTRFS.