Make a slow WordPress site fast!

WD-WordPress-performance.md

WordPress Performance

Debugging theory: https://github.com/szepeviktor/debug-wordpress

• Check PHP version, 8.1 in 2026
• Check PHP directives:
  • memory_limit
  • max_execution_time
  • opcache.memory_consumption
  • opcache.interned_strings_buffer
• Check OPcache status
  • Install query-monitor and https://github.com/szepeviktor/qm-opcache-status
  • Or see the output of opcache_get_status()
• Is Redis server available?
• Add Redis user in redis.conf

  user Example_user reset on +@all -DEBUG ~Example-prefix:* >Example_password

• Check Redis server configuration
  • maxmemory
  • maxmemory-policy
• Enable redis PHP extension
• Install, configure, activate and enable (create the symlink for object-cache.php) wp-redis plugin in wp-config

  $redis_server = [
      'host' => '127.0.0.1',
      'port' => 6379,
      'auth' => 'password', // ['Example_user', 'Example_password'],
      'database' => 1,
  ];
  define('WP_CACHE_KEY_SALT', 'Example-prefix:');

• Delete transients: wp transient delete --all
• Compare CPU load to resource limits: https://gist.github.com/szepeviktor/2f23726aeecf3655abc473160514e1e3
• See your browser's Developer Tools / Network / HTML page request / Timings: DNS, TCP, SSL, page generation
• Reveal detailed timing in Server-Timing HTTP response headers: https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Server-Timing
• Log response times: https://github.com/szepeviktor/wordpress-website-lifecycle/blob/master/debug/debug-response-time.php
• Profile page generation (see HTML comments): https://github.com/szepeviktor/wordpress-website-lifecycle/blob/master/debug/debug-profiling.php
• Install query-monitor plugin for SQL queries, HTTP requests, hooks and many more
• Install and configure SPX PHP profiling extension: https://github.com/NoiseByNorthwest/php-spx
• Add missing SQL indices: https://mariadb.com/docs/server/reference/sql-statements/data-definition/alter/alter-table#add-index
• Delete orphan entities and metadata: https://github.com/humanmade/orphan-command
• Debug HTTP request headers: https://github.com/szepeviktor/wordpress-website-lifecycle/blob/master/debug/debug-request-headers.php
• Debug HTTP POST requests: https://github.com/szepeviktor/wordpress-website-lifecycle/blob/master/debug/debug-post-requests.php
• Rate limit aggressive bots (Facebook/Bing): https://github.com/szepeviktor/php-rate-limiter
• Remove debug tools and delete log files! https://gist.github.com/szepeviktor/d2df7a36f61d31dad1ab9a6a5fb57106