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SCI Profiler PHP — WordPress

Guide to measuring the carbon footprint of a WordPress site with SCI Profiler PHP.

Use Cases and Functional Units

In WordPress every page load is a functional unit. The SCI score for GET /hello-world/ includes everything WordPress does: loading wp-load.php, running plugin hooks, querying the database, rendering the theme template, and sending the response.

Typical use cases

Use Case HTTP Request What Happens Inside
Blog post view GET /2026/03/my-post/ wp-load.php bootstrap, WP_Query, theme template hierarchy, sidebar widgets, wp_footer hooks, output buffering
Homepage GET / Front page query, featured posts, menu rendering, header/footer, all active plugin filters
WooCommerce product page GET /product/red-shirt/ Product query, variable product data, related products, price calculation, add-to-cart form
WooCommerce checkout POST /checkout/ Cart validation, shipping calculation, payment gateway API call, order creation, order confirmation email
Admin dashboard GET /wp-admin/ Admin bootstrap, dashboard widgets, update checks, plugin notices
REST API call GET /wp-json/wp/v2/posts REST controller, permission check, WP_Query, serialization
AJAX heartbeat POST /wp-admin/admin-ajax.php Heartbeat API, autosave check, session refresh
WP-Cron task GET /wp-cron.php Scheduled hooks: post publication, plugin tasks, transient cleanup

Each of these is an independent functional unit measured by the profiler.

Setup

Standard WordPress (Apache)

# /etc/apache2/sites-available/staging-wordpress.conf
<VirtualHost *:80>
    ServerName staging.myblog.local
    DocumentRoot /var/www/wordpress

    # Enable SCI profiling (staging only!)
    # Using phar:
    php_value auto_prepend_file "/opt/sci-profiler.phar"
    # Or using source:
    # php_value auto_prepend_file "/opt/sci-profiler-php/src/bootstrap.php"
</VirtualHost>

WordPress with PHP-FPM (Nginx)

# /etc/nginx/sites-available/staging-wordpress
server {
    server_name staging.myblog.local;
    root /var/www/wordpress;

    location ~ \.php$ {
        # Using phar:
        fastcgi_param PHP_VALUE "auto_prepend_file=/opt/sci-profiler.phar";
        # Or using source:
        # fastcgi_param PHP_VALUE "auto_prepend_file=/opt/sci-profiler-php/src/bootstrap.php";
        fastcgi_pass unix:/run/php/php8.3-fpm.sock;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
    }
}

Laravel Valet / Herd

Create a .user.ini in the WordPress root:

; /var/www/wordpress/.user.ini
; Using phar:
auto_prepend_file = /opt/sci-profiler.phar
; Or using source:
; auto_prepend_file = /opt/sci-profiler-php/src/bootstrap.php

wp-cli (CLI commands)

# Using phar:
php -d auto_prepend_file=/opt/sci-profiler.phar \
  /usr/local/bin/wp cron event run --all
# Or using source:
# php -d auto_prepend_file=/opt/sci-profiler-php/src/bootstrap.php \
#   /usr/local/bin/wp cron event run --all

Configuration Example

<?php
// /opt/sci-profiler-php/config/sci-profiler.local.php
return [
    'enabled'               => true,
    'device_power_watts'    => 18.0,
    'grid_carbon_intensity' => 385.0,      // Germany
    'output_dir'            => '/var/www/wordpress/wp-content/sci-profiler',
    'reporters'             => ['json', 'log', 'html'],
];

Make sure the output directory is not publicly accessible, or add a deny rule in .htaccess:

# wp-content/sci-profiler/.htaccess
Deny from all

Identifying High-Impact Use Cases

After collecting data from a browsing session, analyze by URI pattern:

# Top 10 highest-SCI endpoints
cat /var/www/wordpress/wp-content/sci-profiler/sci-profiler.jsonl \
  | jq -r '[.["request.uri"], .["sci.sci_mgco2eq"], .["time.wall_time_ms"]] | @tsv' \
  | sort -t$'\t' -k2 -rn \
  | head -10
# Average SCI per URI pattern
cat /var/www/wordpress/wp-content/sci-profiler/sci-profiler.jsonl \
  | jq -r '.["request.uri"]' \
  | sort | uniq -c | sort -rn | head -20
# Compare front-end page load vs admin
cat /var/www/wordpress/wp-content/sci-profiler/sci-profiler.jsonl \
  | jq -s '
    group_by(.["request.uri"] | test("wp-admin"))
    | map({
        area: (if .[0]["request.uri"] | test("wp-admin") then "admin" else "frontend" end),
        avg_sci: (map(.["sci.sci_mgco2eq"]) | add / length),
        count: length
      })
  '

Common WordPress Optimization Insights

What the SCI profiler typically reveals in WordPress:

Finding Common Cause Optimization
High SCI on every page Too many active plugins, each adding hooks and queries Audit and disable unused plugins
admin-ajax.php dominates Heartbeat API firing every 15-60 seconds Increase heartbeat interval or disable on front-end
wp-cron.php spikes Accumulated scheduled tasks running on page load Switch to system cron (define('DISABLE_WP_CRON', true);)
Product pages 5x blog posts WooCommerce related products query, variable product data Enable object cache (Redis/Memcached), limit related products
High memory on homepage Loading all posts with full content for excerpts Use WP_Query with 'fields' => 'ids' or proper pagination
Slow REST API responses Missing persistent object cache, no query result caching Install Redis object cache, add Cache-Control headers

Full Page Load Measurement

A single WordPress page load may trigger multiple requests. To measure the total carbon cost of a user viewing a page:

# Simulate a full page load and measure
# 1. The main HTML page
curl -s http://staging.myblog.local/2026/03/my-post/ > /dev/null

# 2. Check what PHP-generated resources the page loads
curl -s http://staging.myblog.local/2026/03/my-post/ \
  | grep -oP 'src="[^"]*\.php[^"]*"' \
  | sed 's/src="//;s/"//' \
  | while read url; do curl -s "$url" > /dev/null; done

# 3. Aggregate the SCI for all requests in the last 30 seconds
cat /var/www/wordpress/wp-content/sci-profiler/sci-profiler.jsonl \
  | jq -s 'map(.["sci.sci_mgco2eq"]) | {total_mgco2eq: add, requests: length}'

WooCommerce Checkout Journey

To measure the complete carbon cost of a purchase flow:

# Filter requests from a checkout session
cat /var/www/wordpress/wp-content/sci-profiler/sci-profiler.jsonl \
  | jq 'select(.["request.uri"] | test("/cart|/checkout|wc-ajax|payment"))' \
  | jq -s '{
      journey: "checkout",
      steps: length,
      total_mgco2eq: map(.["sci.sci_mgco2eq"]) | add,
      total_time_ms: map(.["time.wall_time_ms"]) | add,
      heaviest: max_by(.["sci.sci_mgco2eq"]) | .["request.uri"]
    }'