Apple implemented Siri on macOS Sierra. Siri is a very cool feature specially if you use it on iPhone. But if you don’t use it probably it is slowing down your Mac. Check here how to enable / disable Siri on Mac.
You can enable or disable Siri on macOS Sierra anytime you want. For that, Go to “System Preferences” > and select “Siri“.
Once you’re on Siri settings you can enable or disable it, set your language for Siri, set the Siri Voice, turn On/Off the voice feedback, set the Mic input and the keyboard shortcut to launch Siri.
You can also set or unset “show Siri menu bar”.
To enable / disable Siri just check / uncheck the checkbox under the Siri icon on this screen.
If you are ware about Siri privacy details, you may read the “About Siri and Privacy” tab.