Some optimizations for WordPress, see http://blog.alexz.me/wp-opengraph for more info

functions.php

<?php
function disable_emojis() {
	remove_action( 'wp_head', 'print_emoji_detection_script', 7 );
	remove_action( 'admin_print_scripts', 'print_emoji_detection_script' );
	remove_action( 'wp_print_styles', 'print_emoji_styles' );
	remove_action( 'admin_print_styles', 'print_emoji_styles' );	
	remove_filter( 'the_content_feed', 'wp_staticize_emoji' );
	remove_filter( 'comment_text_rss', 'wp_staticize_emoji' );	
	remove_filter( 'wp_mail', 'wp_staticize_emoji_for_email' );
	add_filter( 'tiny_mce_plugins', 'disable_emojis_tinymce' );
	add_filter( 'wp_resource_hints', 'disable_emojis_remove_dns_prefetch', 10, 2 );
}
add_action( 'init', 'disable_emojis' );

function disable_emojis_tinymce( $plugins ) {
	if ( is_array( $plugins ) ) {
		return array_diff( $plugins, array( 'wpemoji' ) );
	} else {
		return array();
	}
}

function disable_emojis_remove_dns_prefetch( $urls, $relation_type ) {
	if ( 'dns-prefetch' == $relation_type ) {
		$emoji_svg_url = apply_filters( 'emoji_svg_url', 'https://s.w.org/images/core/emoji/2.2.1/svg/' );
		$urls = array_diff( $urls, array( $emoji_svg_url ) );
	}

	return $urls;
}


function remove_script_version( $src ){
	$parts = explode( '?ver=', $src );
	return $parts[0];
}
add_filter('script_loader_src', 'remove_script_version', 15, 1);
add_filter('style_loader_src', 'remove_script_version', 15, 1);


function remove_wp_embed() {
	if (!is_admin()) {
		wp_deregister_script('wp-embed');
	}
}
add_action('init', 'remove_wp_embed');

add_filter('rest_enabled', '__return_false');
remove_action( 'xmlrpc_rsd_apis', 'rest_output_rsd' );
remove_action( 'wp_head', 'rest_output_link_wp_head', 10, 0 );
remove_action( 'template_redirect', 'rest_output_link_header', 11, 0 );
remove_action( 'auth_cookie_malformed', 'rest_cookie_collect_status' );
remove_action( 'auth_cookie_expired', 'rest_cookie_collect_status' );
remove_action( 'auth_cookie_bad_username', 'rest_cookie_collect_status' );
remove_action( 'auth_cookie_bad_hash', 'rest_cookie_collect_status' );
remove_action( 'auth_cookie_valid', 'rest_cookie_collect_status' );
remove_filter( 'rest_authentication_errors', 'rest_cookie_check_errors', 100 );
remove_action( 'init', 'rest_api_init' );
remove_action( 'rest_api_init', 'rest_api_default_filters', 10, 1 );
remove_action( 'parse_request', 'rest_api_loaded' );
remove_action( 'rest_api_init', 'wp_oembed_register_route');
remove_filter( 'rest_pre_serve_request', '_oembed_rest_pre_serve_request', 10, 4 );
remove_action( 'wp_head', 'wp_oembed_add_discovery_links' );
remove_action( 'wp_head', 'wp_oembed_add_host_js' );
remove_filter( 'oembed_dataparse', 'wp_filter_oembed_result', 10 );
add_filter( 'embed_oembed_discover', '__return_false' );
add_filter( 'rewrite_rules_array', 'disable_embeds_rewrites' );

remove_action('rss_head', 'wp_generator');
//remove_action('rss2_head', 'the_generator');
//remove_action('commentsrss2_head', 'wp_generator');
remove_action('atom_head', 'wp_generator');
remove_action('wp_head', 'wp_generator');
remove_action('wp_head', 'rsd_link');
//remove_action('wp_head', 'feed_links', 2);
//remove_action('wp_head', 'feed_links_extra', 3 );
remove_action('wp_head', 'wlwmanifest_link');
remove_action('wp_head', 'wp_shortlink_wp_head', 10, 0 );
remove_action('wp_head', 'adjacent_posts_rel_link_wp_head', 10, 0 );

/*
add_filter( 'xmlrpc_methods', 'sar_block_xmlrpc_attacks' );
function sar_block_xmlrpc_attacks( $methods ) {
   unset( $methods['pingback.ping'] );
   unset( $methods['pingback.extensions.getPingbacks'] );
   return $methods;
}

add_filter( 'wp_headers', 'sar_remove_x_pingback_header' );
function sar_remove_x_pingback_header( $headers ) {
   unset( $headers['X-Pingback'] );
   return $headers;
}

add_action('wp', function() {
	header_remove('X-Pingback');
}, 1000);
*/
?>