code snippets for functions.php to increase performance

performance-boost-code-snippets-functions.php

<?php 

/**
 * Disable jQuery Migrate in WordPress.
 *
 */
function crave_remove_jquery_migrate( &$scripts) {
	if(!is_admin()) {
		$scripts->remove('jquery');
	}
}
add_action( 'wp_default_scripts', 'crave_remove_jquery_migrate' );

/**
* Function to defer all scripts which are not excluded
*/
function crave_js_defer_attr($tag) {
	if (is_admin()) {
		return $tag;
	}
	// Do not add defer attribute to these scripts
	$scripts_to_exclude = array('jquery.js'); // add a string of js file e.g. script.js

	foreach($scripts_to_exclude as $exclude_script) {
		if (true == strpos($tag, $exclude_script ) )
			return $tag; 
	}
	// Defer all remaining scripts not excluded above
	return str_replace( ' src', ' async src', $tag );
}
add_filter( 'script_loader_tag', 'crave_js_defer_attr', 10);


/**
* Remove junk from head
*/
// remove WordPress version number
function crave_remove_version() {
	return '';
}
add_filter('the_generator', 'crave_remove_version');

remove_action('wp_head', 'wp_generator');
remove_action('wp_head', 'rsd_link'); // remove really simple discovery (RSD) link
remove_action('wp_head', 'wlwmanifest_link'); // remove wlwmanifest.xml (needed to support windows live writer)
remove_action('wp_head', 'feed_links', 2); // remove rss feed links (if you don't use rss)
remove_action('wp_head', 'feed_links_extra', 3); // removes all extra rss feed links
remove_action('wp_head', 'index_rel_link'); // remove link to index page
remove_action('wp_head', 'start_post_rel_link', 10, 0); // remove random post link
remove_action('wp_head', 'parent_post_rel_link', 10, 0); // remove parent post link
remove_action('wp_head', 'adjacent_posts_rel_link', 10, 0); // remove the next and previous post links
remove_action('wp_head', 'adjacent_posts_rel_link_wp_head', 10, 0 );
remove_action('wp_head', 'wp_shortlink_wp_head', 10, 0 ); // remove shortlink

/**
 * Disable embeds
 */
function crave_disable_embeds() {
	
	// 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 discovery links.
	remove_action( 'wp_head', 'wp_oembed_add_discovery_links' );
	
	// 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', 'crave_disable_embeds_tiny_mce_plugin' );
	
	// Remove all embeds rewrite rules.
	add_filter( 'rewrite_rules_array', 'crave_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', 'crave_disable_embeds', 9999 );
	
function crave_disable_embeds_tiny_mce_plugin($plugins) {
	return array_diff($plugins, array('wpembed'));
}
	
function crave_disable_embeds_rewrites($rules) {
	foreach($rules as $rule => $rewrite) {
		if(false !== strpos($rewrite, 'embed=true')) {
			unset($rules[$rule]);
		}
	}
	return $rules;
}
/**
* Remove block-library-css
*/
function wpassist_remove_block_library_css(){
    wp_dequeue_style( 'wp-block-library' );
} 
add_action( 'wp_enqueue_scripts', 'wpassist_remove_block_library_css' );

/**
* Remove svg plugin css
*/
add_action( 'wp_print_styles', 'deregister_my_styles', 100 );
function deregister_my_styles() {
	wp_deregister_style( 'bodhi-svgs-attachment' );
}

?>