WordPress Performance

Optimize WordPress for Core Web Vitals (LCP, INP, CLS) and server response times. Focus on measurable improvements with highest impact.

Core Web Vitals

LCP (Largest Contentful Paint) — Target: < 2.5s

Identify the largest visible element and optimize its load path:

•Preload LCP image: <link rel="preload" as="image" href="hero.webp">
•Remove render-blocking CSS for above-the-fold content
•Optimize server response time (TTFB < 800ms)
•Use fetchpriority="high" on LCP image

INP (Interaction to Next Paint) — Target: < 200ms

Reduce JavaScript execution blocking interaction:

•Defer non-critical JavaScript
•Break long tasks into smaller chunks
•Use requestIdleCallback for non-urgent work
•Avoid heavy click handlers on main thread

CLS (Cumulative Layout Shift) — Target: < 0.1

Prevent layout shifts:

•Set width and height on all images
•Use aspect-ratio CSS for responsive images
•Reserve space for dynamic content (ads, embeds)
•Avoid inserting content above existing content

PHP Performance

Avoid Expensive Operations on Every Page Load

php

// BAD: Runs on every request
add_action( 'init', function() {
    $data = expensive_api_call();
} );

// GOOD: Cache the result
add_action( 'init', function() {
    $data = get_transient( 'my_api_data' );
    if ( false === $data ) {
        $data = expensive_api_call();
        set_transient( 'my_api_data', $data, HOUR_IN_SECONDS );
    }
} );

Object Cache

php

// Use wp_cache for frequently accessed data
$value = wp_cache_get( 'my_key', 'my_group' );
if ( false === $value ) {
    $value = compute_expensive_value();
    wp_cache_set( 'my_key', $value, 'my_group', 3600 );
}

N+1 Query Prevention

php

// BAD: One query per post
foreach ( $posts as $post ) {
    $meta = get_post_meta( $post->ID, 'my_meta', true );
}

// GOOD: Prime the cache first
update_postmeta_cache( wp_list_pluck( $posts, 'ID' ) );
foreach ( $posts as $post ) {
    $meta = get_post_meta( $post->ID, 'my_meta', true ); // Uses cache
}

Database Optimization

Efficient Queries

php

// BAD: meta_query with LIKE
'meta_query' => [
    [ 'key' => 'color', 'value' => 'blue', 'compare' => 'LIKE' ]
]

// GOOD: Exact match or taxonomy
'meta_query' => [
    [ 'key' => 'color', 'value' => 'blue', 'compare' => '=' ]
]

Query Optimizations

•Use 'fields' => 'ids' when you only need IDs
•Use 'no_found_rows' => true when you don't need pagination
•Use 'update_post_meta_cache' => false when you don't need meta
•Use 'update_post_term_cache' => false when you don't need terms

php

$query = new WP_Query( [
    'post_type'              => 'post',
    'posts_per_page'         => 10,
    'no_found_rows'          => true,
    'update_post_meta_cache' => false,
    'update_post_term_cache' => false,
] );

Custom Table Indexes

php

// Add index for frequently queried columns
$wpdb->query( "CREATE INDEX idx_custom_col ON {$wpdb->prefix}my_table (custom_col)" );

Asset Loading

Conditional Loading

php

// Only load on pages that need it
add_action( 'wp_enqueue_scripts', function() {
    if ( ! is_singular( 'product' ) ) {
        return;
    }
    wp_enqueue_script( 'product-gallery', ... );
} );

Defer / Async

php

// Defer non-critical scripts
add_filter( 'script_loader_tag', function( $tag, $handle ) {
    if ( 'my-script' === $handle ) {
        return str_replace( ' src', ' defer src', $tag );
    }
    return $tag;
}, 10, 2 );

Critical CSS

Inline critical CSS and defer the rest:

php

add_action( 'wp_head', function() {
    echo '<style>' . file_get_contents( get_template_directory() . '/critical.css' ) . '</style>';
} );

WordPress 6.9+ Optimizations

•On-demand CSS loading for classic themes
•Speculative loading API for prefetching
•Block-level asset loading — scripts/styles per block, not global
•Lazy loading built into core for images and iframes

Caching Strategy

Layer	Tool	TTL
Object cache	Redis/Memcached	Persistent
Transients	`set_transient()`	Hours/days
Fragment cache	`wp_cache_get()`	Minutes
Full page	Varnish/CDN	Minutes
Browser	`Cache-Control` headers	Hours/days