WdMyCloud extremely unresponsive and slow

My Cloud OS 3 Personal & Network Attached Storage My Cloud
4

Please read the following post which will explain what is happening.
http://community.wd.com/t5/WD-My-Cloud/before-you-pack-up-your-WD-and-return-it-let-s-talk-about/td-p/683307
If you ssh into your MyCloud and kill the indexing processes, you should be able to have a functioning device. Think about downgrading the firmware too. Search for the post on this topic.