The option you are looking for is Enable/Disable Cloud Service from the dashboard’s Settings tab (under General). If you had read the release notes for the latest firmware (which is your duty to read everytime you upgrade the firmware), you’d have learnt of this in there. With the latest firmware if you disable cloud service that indexing functionality will be turned off.
Only you can decide if cloud service is important to you or not. You can of course still access all your data from outside the network using various other methods - ftp, WebDAV, web file viewer, etc. Just that you won’t be able to use the mobile or desktop apps to access your files from outside the network…but they should all be accessible from within the network using network mapped drives (and possibly the desktop app as well but I never installed the desktop or mobile app so I can’t say if those will work but I suspect without the indexing functionality the mobile app won’t work but the desktop app probably will).
As I have told others before, if you find that copying of lots of media files is bringing your device to its knees then just split the copy operation into multiple smaller batches. That is expected when you copy thousands or tens of thousands of files all at once, esp. since EX2 has a weak cpu and just 512MB of memory (no wonder it’s much cheaper than the leading NASes). But the file copy speeds within network is pretty good on a wired connection.
BTW, this post mentions a lot of the ssh steps in great detail -> http://community.wd.com/t5/WD-My-Cloud-EX2/Firmware-1-05-21-File-copy-fails-due-to-long-wdmc-paths/m-p/829476#M1993
But if you aren’t familiar with using SSH then just do what I mentioned above from the dashboard.