I have 35TB of mostly video on an unraid server too. MC17 has been unstable for me too - with long pauses between changing views, or outright hangs. These are not consistent, however, so I haven't figured out when they're most likely to occur. MC16 was like this at first, but then the majority of the builds were very stable.
Tonight, when tagging, I'd switch from say Media type = TV show to Movies in a panes view... would then have to read some forums or something while MC did its thing, returning after multiple minutes. During that time it was even impossible to switch to MC using the task bar.