How to disable animation on opening Notification Centre in macOS? I couldn't find it here. Perhaps you can't disable it but if you can I would love to know how. 

My preference is for Notification Centre to open instantly.
Absolutely, if you are after a snappier mac by saving those precious seconds here and there, I believe the best option is to go into the System Preferences and turning on Reduce Motion in the Accessibility tab.

Turning on Reduced Motion




This makes the Notification Centre slide-in animation instant. I hope that helps you out, it really makes a difference. Definitely, let me know how you get on.