Dude.
You are in the wrong section. The New MyCloud Home doesn’t even has a Dashboard UI and it was released in august.
For the classic My cloud and my cloud mirror, What is probably happening to you is that you might have enabled the cloud access or media service (DLNA). Even if you didn’t enabled the cloud access in Dashboard, it is automatically enabled if you login in the WD mobile app. You can access the dashboard and disable cloud access and media serving, reboot the device and your device will run smoothy again.
I have had this same problem since I bought a WD MYCloud Mirror 8 TB 2 Gen. I am using the cloud access disabled all the time because of that. My problems were related here.
I think I gonna buy the New Mycloud Home Duo, it has better processor and better RAM, and a simpler interface, it should run smoother than the My Cloud Mirror
