Your Mac is designed to handle multiple users if you need to share it with family members, friends or work colleagues.
The way it’s setup, it’s the equivalent of each user having his own Mac and no content is shared between users.
To quickly switch between users, if you’ve enabled “Show fast user switching menu as Full Name” in the System Preferences > Users & Groups, you can simply click the name of the current user on the top right corner of your display, on the menu bar and select another user to login.
Although your Mac is powerful enough to handle multiple users at once, an iMac that is plugged into power and on a desk will handle it better than a Macbook Air on battery power.
If you’re travelling and trying to save battery and improve performance, meaning making your Mac faster, then we would recommend to logout any user who’s no longer using the Mac.
To do so, simply login to the user account that is no longer needed, click the black Apple icon on the top left corner of your display then select “Log out [name of the current user]”.
This way, your Mac will no longer use performance to keep this user logged in and conserve it for the single user that is currently active instead.
You should be able to see a clear performance improvement on your Mac and enjoy it to the full for your user session.