roi-theme/wp-content/themes/apus-theme/inc/performance.php

<?php
/**
 * Performance Optimization Functions
 *
 * Functions to remove WordPress bloat and improve performance.
 *
 * @package Apus_Theme
 * @since 1.0.0
 */

// Exit if accessed directly.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Disable WordPress Emojis
 *
 * Removes emoji detection scripts and styles from WordPress.
 * These scripts are loaded on every page but rarely used.
 *
 * @since 1.0.0
 */
function apus_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' );

	// Remove from TinyMCE.
	add_filter( 'tiny_mce_plugins', 'apus_disable_emojis_tinymce' );
	add_filter( 'wp_resource_hints', 'apus_disable_emojis_remove_dns_prefetch', 10, 2 );
}
add_action( 'init', 'apus_disable_emojis' );

/**
 * Filter function used to remove emoji plugin from TinyMCE
 *
 * @since 1.0.0
 * @param array $plugins An array of default TinyMCE plugins.
 * @return array Modified array of TinyMCE plugins without emoji plugin.
 */
function apus_disable_emojis_tinymce( $plugins ) {
	if ( is_array( $plugins ) ) {
		return array_diff( $plugins, array( 'wpemoji' ) );
	}

	return array();
}

/**
 * Remove emoji CDN hostname from DNS prefetching hints
 *
 * @since 1.0.0
 * @param array  $urls          URLs to print for resource hints.
 * @param string $relation_type The relation type the URLs are printed for.
 * @return array Modified array of URLs.
 */
function apus_disable_emojis_remove_dns_prefetch( $urls, $relation_type ) {
	if ( 'dns-prefetch' === $relation_type ) {
		// Strip out any URLs referencing the WordPress.org emoji location.
		$emoji_svg_url_bit = 'https://s.w.org/images/core/emoji/';
		foreach ( $urls as $key => $url ) {
			if ( strpos( $url, $emoji_svg_url_bit ) !== false ) {
				unset( $urls[ $key ] );
			}
		}
	}

	return $urls;
}

/**
 * Disable WordPress oEmbed
 *
 * Removes oEmbed discovery links and scripts.
 * Only disable if you don't need to embed content from other sites.
 *
 * @since 1.0.0
 */
function apus_disable_oembed() {
	// 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' );

	// Remove all embeds rewrite rules.
	add_filter( 'rewrite_rules_array', 'apus_disable_oembed_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', 'apus_disable_oembed', 9999 );

/**
 * Remove all rewrite rules related to embeds
 *
 * @since 1.0.0
 * @param array $rules WordPress rewrite rules.
 * @return array Modified rewrite rules.
 */
function apus_disable_oembed_rewrites( $rules ) {
	foreach ( $rules as $rule => $rewrite ) {
		if ( false !== strpos( $rewrite, 'embed=true' ) ) {
			unset( $rules[ $rule ] );
		}
	}
	return $rules;
}

/**
 * Disable wp-embed.js script
 *
 * Dequeues the wp-embed.js script that WordPress loads by default.
 * This script is used for embedding WordPress posts on other sites.
 *
 * @since 1.0.0
 */
function apus_dequeue_embed_script() {
	wp_deregister_script( 'wp-embed' );
}
add_action( 'wp_footer', 'apus_dequeue_embed_script' );

/**
 * Disable WordPress Feeds
 *
 * Removes RSS, RDF, and Atom feeds.
 * Only disable if you don't need feed functionality.
 *
 * @since 1.0.0
 */
function apus_disable_feeds() {
	wp_die(
		esc_html__( 'No feed available, please visit our homepage!', 'apus' ),
		esc_html__( 'Feed Not Available', 'apus' ),
		array(
			'response'  => 404,
			'back_link' => true,
		)
	);
}

/**
 * Remove feed links and redirect feed URLs
 *
 * @since 1.0.0
 */
function apus_disable_feed_links() {
	// Remove feed links from header.
	remove_action( 'wp_head', 'feed_links', 2 );
	remove_action( 'wp_head', 'feed_links_extra', 3 );

	// Redirect feed URLs to homepage.
	add_action( 'do_feed', 'apus_disable_feeds', 1 );
	add_action( 'do_feed_rdf', 'apus_disable_feeds', 1 );
	add_action( 'do_feed_rss', 'apus_disable_feeds', 1 );
	add_action( 'do_feed_rss2', 'apus_disable_feeds', 1 );
	add_action( 'do_feed_atom', 'apus_disable_feeds', 1 );
	add_action( 'do_feed_rss2_comments', 'apus_disable_feeds', 1 );
	add_action( 'do_feed_atom_comments', 'apus_disable_feeds', 1 );
}
add_action( 'init', 'apus_disable_feed_links' );

/**
 * Disable RSD and Windows Live Writer Manifest
 *
 * Really Simple Discovery (RSD) and Windows Live Writer (WLW) manifest
 * are rarely used and can be safely removed.
 *
 * @since 1.0.0
 */
function apus_disable_rsd_wlw() {
	// Remove RSD link.
	remove_action( 'wp_head', 'rsd_link' );

	// Remove Windows Live Writer manifest link.
	remove_action( 'wp_head', 'wlwmanifest_link' );
}
add_action( 'init', 'apus_disable_rsd_wlw' );

/**
 * Disable Dashicons for non-logged users
 *
 * Dashicons are only needed in the admin area and for logged-in users.
 * This removes them from the front-end for visitors.
 *
 * @since 1.0.0
 */
function apus_disable_dashicons() {
	if ( ! is_user_logged_in() ) {
		wp_deregister_style( 'dashicons' );
	}
}
add_action( 'wp_enqueue_scripts', 'apus_disable_dashicons' );

/**
 * Disable Block Library CSS
 *
 * Removes the default WordPress block library styles.
 * Only disable if you're not using the block editor or if you're
 * providing your own block styles.
 *
 * @since 1.0.0
 */
function apus_disable_block_library_css() {
	// Remove default block library styles.
	wp_dequeue_style( 'wp-block-library' );
	wp_dequeue_style( 'wp-block-library-theme' );

	// Remove inline global styles.
	wp_dequeue_style( 'global-styles' );

	// Remove classic theme styles (if not using classic editor).
	wp_dequeue_style( 'classic-theme-styles' );
}
add_action( 'wp_enqueue_scripts', 'apus_disable_block_library_css', 100 );

/**
 * Remove WordPress version from head and feeds
 *
 * Removes the WordPress version number for security reasons.
 *
 * @since 1.0.0
 */
function apus_remove_wp_version() {
	return '';
}
add_filter( 'the_generator', 'apus_remove_wp_version' );

/**
 * Disable XML-RPC
 *
 * XML-RPC is often targeted by brute force attacks.
 * Disable if you don't need remote publishing functionality.
 *
 * @since 1.0.0
 * @return bool
 */
function apus_disable_xmlrpc() {
	return false;
}
add_filter( 'xmlrpc_enabled', 'apus_disable_xmlrpc' );

/**
 * Remove jQuery Migrate
 *
 * jQuery Migrate is used for backwards compatibility but adds extra overhead.
 * Only remove if you've verified all scripts work without it.
 *
 * @since 1.0.0
 * @param WP_Scripts $scripts WP_Scripts object.
 */
function apus_remove_jquery_migrate( $scripts ) {
	if ( ! is_admin() && isset( $scripts->registered['jquery'] ) ) {
		$script = $scripts->registered['jquery'];

		if ( $script->deps ) {
			// Remove jquery-migrate from dependencies.
			$script->deps = array_diff( $script->deps, array( 'jquery-migrate' ) );
		}
	}
}
add_action( 'wp_default_scripts', 'apus_remove_jquery_migrate' );

/**
 * Disable REST API for non-logged users
 *
 * Restricts REST API access to authenticated users only.
 * Comment out if you need public REST API access.
 *
 * @since 1.0.0
 * @param WP_Error|null|bool $result Error from another authentication handler, null if not errors.
 * @return WP_Error|null|bool
 */
function apus_disable_rest_api( $result ) {
	if ( ! empty( $result ) ) {
		return $result;
	}

	if ( ! is_user_logged_in() ) {
		return new WP_Error(
			'rest_not_logged_in',
			esc_html__( 'You are not currently logged in.', 'apus' ),
			array( 'status' => 401 )
		);
	}

	return $result;
}
// Uncomment to enable REST API restriction.
// add_filter( 'rest_authentication_errors', 'apus_disable_rest_api' );

/**
 * Remove unnecessary DNS prefetch
 *
 * Removes DNS prefetch for s.w.org (WordPress.org stats).
 *
 * @since 1.0.0
 * @param array  $hints          DNS prefetch hints.
 * @param string $relation_type  The relation type.
 * @return array Modified hints.
 */
function apus_remove_dns_prefetch( $hints, $relation_type ) {
	if ( 'dns-prefetch' === $relation_type ) {
		// Remove s.w.org from hints to avoid WordPress.org connections
		$filtered_hints = array();
		foreach ( $hints as $hint ) {
			if ( strpos( $hint, 's.w.org' ) === false ) {
				$filtered_hints[] = $hint;
			}
		}
		return $filtered_hints;
	}

	return $hints;
}
add_filter( 'wp_resource_hints', 'apus_remove_dns_prefetch', 10, 2 );

/**
 * Disable heartbeat API
 *
 * The heartbeat API can cause high CPU usage.
 * This limits it to the post editor only.
 *
 * @since 1.0.0
 * @param array $settings Heartbeat settings.
 * @return array Modified settings.
 */
function apus_modify_heartbeat_settings( $settings ) {
	// Disable everywhere except post editor.
	global $pagenow;

	if ( 'post.php' !== $pagenow && 'post-new.php' !== $pagenow ) {
		wp_deregister_script( 'heartbeat' );
	}

	return $settings;
}
add_filter( 'heartbeat_settings', 'apus_modify_heartbeat_settings' );

/**
 * Disable WordPress Core Lazy Loading
 *
 * WordPress 5.5+ adds native lazy loading which can conflict with
 * custom image optimization. Only disable if using custom lazy loading.
 *
 * @since 1.0.0
 * @param string $value Loading attribute value.
 * @return string Modified loading attribute.
 */
function apus_disable_wp_lazy_loading( $value ) {
	// Return false to disable or keep 'lazy' to enable
	// We keep it enabled as it's good for performance
	return $value;
}
// Uncomment to disable native lazy loading if needed
// add_filter( 'wp_lazy_loading_enabled', '__return_false' );

/**
 * Remove Query Strings from Static Resources
 *
 * Some caching services and CDNs have issues with query strings.
 * This removes version query strings from CSS and JS files.
 *
 * @since 1.0.0
 * @param string $src Source URL.
 * @return string Modified source URL.
 */
function apus_remove_query_strings( $src ) {
	if ( strpos( $src, '?ver=' ) ) {
		$src = remove_query_arg( 'ver', $src );
	}
	return $src;
}
// Uncomment to enable query string removal
// add_filter( 'style_loader_src', 'apus_remove_query_strings', 10, 1 );
// add_filter( 'script_loader_src', 'apus_remove_query_strings', 10, 1 );

/**
 * Defer Parsing of JavaScript
 *
 * Adds defer attribute to non-critical scripts to improve page load speed.
 *
 * @since 1.0.0
 * @param string $tag    The script tag.
 * @param string $handle The script handle.
 * @param string $src    The script source URL.
 * @return string Modified script tag.
 */
function apus_defer_parsing_of_js( $tag, $handle, $src ) {
	// Skip if already has async or defer
	if ( strpos( $tag, 'defer' ) !== false || strpos( $tag, 'async' ) !== false ) {
		return $tag;
	}

	// List of scripts that should NOT be deferred (critical scripts)
	$no_defer_scripts = array(
		'jquery',
		'jquery-core',
		'jquery-migrate',
	);

	// Don't defer these scripts
	if ( in_array( $handle, $no_defer_scripts, true ) ) {
		return $tag;
	}

	// Add defer attribute
	return str_replace( ' src', ' defer src', $tag );
}
// Uncomment to enable script deferring
// add_filter( 'script_loader_tag', 'apus_defer_parsing_of_js', 10, 3 );

/**
 * Preload Critical Resources
 *
 * Adds preload links for critical resources like fonts and above-fold images.
 *
 * @since 1.0.0
 */
function apus_preload_critical_resources() {
	// Preload critical fonts (update paths as needed)
	// Example:
	// echo '<link rel="preload" href="' . get_template_directory_uri() . '/assets/fonts/font.woff2" as="font" type="font/woff2" crossorigin>';

	// You can add more preload directives here based on your theme's needs
}
add_action( 'wp_head', 'apus_preload_critical_resources', 1 );

/**
 * Add DNS Prefetch for External Domains
 *
 * Adds DNS prefetch hints for external resources to speed up loading.
 *
 * @since 1.0.0
 */
function apus_add_dns_prefetch() {
	// Add DNS prefetch for common external resources
	echo '<link rel="dns-prefetch" href="//fonts.googleapis.com">' . "\n";
	echo '<link rel="dns-prefetch" href="//fonts.gstatic.com">' . "\n";
	// Add more as needed for your external resources
}
// Temporarily disabled to avoid conflicts with apus_remove_dns_prefetch
// add_action( 'wp_head', 'apus_add_dns_prefetch', 0 );

/**
 * Optimize WordPress Database Queries
 *
 * Removes unnecessary meta queries for better performance.
 *
 * @since 1.0.0
 */
function apus_optimize_queries() {
	// Remove unnecessary post meta from queries
	remove_action( 'wp_head', 'adjacent_posts_rel_link_wp_head', 10 );
	remove_action( 'wp_head', 'wp_shortlink_wp_head', 10 );
}
add_action( 'init', 'apus_optimize_queries' );

/**
 * Disable WordPress Admin Bar for Non-Admins
 *
 * Reduces HTTP requests for non-admin users.
 *
 * @since 1.0.0
 */
function apus_disable_admin_bar() {
	if ( ! current_user_can( 'administrator' ) && ! is_admin() ) {
		show_admin_bar( false );
	}
}
add_action( 'after_setup_theme', 'apus_disable_admin_bar' );