The issue of slowness has MORE to do with the constant and poor coding used for rescanning/indexing of files by Western Digital. The default setting for rescanning/indexing is -1 which basically means re-index after ANY change. The process can take many hours.
I followed this page and corrected the issue. https://seo-michael.co.uk/improving-the-performance-of-wd-mycloud/
The essential change I made to improve performance is here:
1- through your browser, go to twonky (http://wdmycloud.local:9000/)
2- go to advanced
3- go to rescan intervals
4 – change it to 0 (or a larger value in minutes. 1440 is every 24 hours)
5- save (at bottom) this stops it scanning itself completely every time a file moves.
6- go and rescan your database
If the value is set to 0, then if you make changes to your file structure go back to advanced and select rescan.
By following the above steps your NAS will work better.