Completely removes the WordPress Heartbeat by deregistering the script.

snippet.php

<?php
// Download this snippet as a plugin and more at: https://wordbits.io/snippet/completely-remove-the-wordpress-heartbeat/
// Created by: jeffmatson
?>

<?php
// Fire the action on init.
add_action( 'init', 'kill_wp_heartbeat' );
function kill_wp_heartbeat() {
    // Deregister the script.
    wp_deregister_script('heartbeat');
}