Globally disable all third-party calls to gravatar.com
Disable Gravatar is a simple plugin that disables all Gravatar's and calls to their 3rd party servers. Gravatar is a “globally recognized avatar” that displays avatars for users and commentators. Gravatar comes built in WordPress by default. Every time a page is loaded on the front-end or the back-end calls are made to gravatar.com servers to check if a user using a particular email address has uploaded a custom image to Gravatar. In some cases, this can cause privacy concerns and/or performance issues.
Increase Your WordPress Privacy
Gravatar's are loaded from a third-party server, the owners of the server can see who is visiting, what the user is visiting, and when the user has visited. Disabling these external calls adds extra layer of privacy to your website by stopping the transmission of email addresses to a service a large portion of people do not even use.
Faster Page Loads
Gravatars can slow down your website because each time it needs to show a Gravatar for a user it has to connect to the gravatar.com servers and get the image. This can add several extra calls to your page load and slow things down if for example your page is displaying 200 comments and your website needs to connect to gravatar.com 200 times.