How to disable embeds in WordPress

Embeds were released with WordPress 4.4. However, with this came some extra inline code they add to your site (link rel tags), including a JavaScript file (wp-embed.min.js). You can disable embeds altogether to speed things up.

function disable_embeds_init() {
    // Remove the REST API endpoint.
    remove_action('rest_api_init', 'wp_oembed_register_route');
 
    // Turn off oEmbed auto discovery.
    add_filter('embed_oembed_discover', '__return_false');
 
    // Don't filter oEmbed results.
    remove_filter('oembed_dataparse', 'wp_filter_oembed_result', 10);
 
    // Remove oEmbed-specific JavaScript from the front-end and back-end.
    remove_action('wp_head', 'wp_oembed_add_host_js');
    add_filter('tiny_mce_plugins', 'disable_embeds_tiny_mce_plugin');
 
    // Remove all embeds rewrite rules.
    add_filter('rewrite_rules_array', 'disable_embeds_rewrites');
 
    // Remove filter of the oEmbed result before any HTTP requests are made.
    remove_filter('pre_oembed_result', 'wp_filter_pre_oembed_result', 10);
}
add_action('init', 'disable_embeds_init', 9999);
 
/**
 * Removes the 'wpembed' TinyMCE plugin.
 *
 * @param array $plugins List of TinyMCE plugins.
 * @return array The modified list.
 */
function disable_embeds_tiny_mce_plugin($plugins) {
    return array_diff($plugins, array('wpembed'));
}
 
/**
 * Remove all rewrite rules related to embeds.
 *
 * @param array $rules WordPress rewrite rules.
 * @return array Rewrite rules without embeds rules.
 */
function disable_embeds_rewrites($rules) {
    foreach ($rules as $rule => $rewrite) {
        if (false !== strpos($rewrite, 'embed=true')) {
            unset($rules[$rule]);
        }
    }
 
    return $rules;
}