Booting WordPress in 10ms: Using SHORTINIT for Ultra-Light Scripts

WordPress is powerful—but it’s also heavy.

Even the simplest request loads plugins, themes, translations, hooks, and a large portion of core. For many use cases, that’s unnecessary overhead.

This is where SHORTINIT comes in.

SHORTINIT allows you to partially boot WordPress, loading only the minimal core required—often reducing execution time dramatically.

What is SHORTINIT?

SHORTINIT is a constant that tells WordPress to stop loading early in the boot process.

<?php
define( 'SHORTINIT', true );
require_once __DIR__ . '/wp-load.php';

When enabled, WordPress loads only a subset of core files and skips most of its normal initialization pipeline.

What Loads vs What Doesn’t

✅ What DOES Load

• Basic constants
• Database access ($wpdb)
• Core utility functions
• Minimal environment setup

❌ What DOES NOT Load

• Plugins (including MU plugins)
• Themes
• Rewrite rules
• Query system (WP_Query)
• Hooks like init, wp_loaded
• Authentication system
• REST API

Important: This is not “light WordPress”—it’s a barebones core layer.

Performance Comparison

// Normal WordPress load
~100–300ms

// SHORTINIT load
~5–15ms

The exact numbers depend on hosting, but the difference is often massive.

Basic Example: Fast Database Query Endpoint

<?php

define( 'SHORTINIT', true );
require_once __DIR__ . '/wp-load.php';

global $wpdb;

$result = $wpdb->get_var("SELECT COUNT(*) FROM {$wpdb->posts}");

header('Content-Type: application/json');
echo json_encode([
    'post_count' => (int) $result
]);

This runs without loading plugins or themes—making it extremely fast.

Use Cases for SHORTINIT

1. Internal APIs

When you need fast endpoints without REST API overhead.

2. Cron Jobs

<?php

define( 'SHORTINIT', true );
require_once __DIR__ . '/wp-load.php';

// perform cleanup
global $wpdb;
$wpdb->query("DELETE FROM {$wpdb->options} WHERE option_name LIKE '_transient_%'");

3. CLI Tools

Custom scripts interacting with the database or basic WordPress config.

4. Health Checks

Fast monitoring endpoints without full application load.

Advanced Example: Manual User Lookup

Since user APIs are not loaded, you must query manually:

<?php

define( 'SHORTINIT', true );
require_once __DIR__ . '/wp-load.php';

global $wpdb;

$user = $wpdb->get_row(
    $wpdb->prepare(
        "SELECT ID, user_email FROM {$wpdb->users} WHERE user_login = %s",
        'admin'
    )
);

echo json_encode($user);

Limitations (Critical to Understand)

1. No Plugin System

Any logic relying on plugins will not work.

2. No Hooks

Hooks like init or plugins_loaded never fire.

3. No Authentication

You cannot rely on WordPress login/session APIs.

4. No REST API

You must build your own endpoints.

5. Limited Core Functions

Many helper functions are unavailable unless manually included.

Extending SHORTINIT (Selective Loading)

You can manually include specific parts of WordPress:

<?php

define( 'SHORTINIT', true );
require_once __DIR__ . '/wp-load.php';

// manually load pluggable functions
require_once ABSPATH . WPINC . '/pluggable.php';

// now you can use some auth functions
if ( \is_user_logged_in() ) {
    echo "User is logged in";
}

This allows a hybrid approach—still fast, but slightly more capable.

When NOT to Use SHORTINIT

• Building full frontend pages
• When plugin logic is required
• When hooks or filters are needed
• Complex business logic relying on WP APIs

SHORTINIT is best for controlled, minimal tasks.

Key Insight

SHORTINIT is not just a performance trick—it’s a way to treat WordPress as a library rather than a full application.

Once you understand this, you can build:

• Ultra-fast endpoints
• Background workers
• Custom integrations

FAQ