Suggested by mikeytown2 for faster Drupal DB

settings.php

<?php

  /**
   * Suggested by mikeytown2 for faster DB
   * @see https://www.drupal.org/node/1650930#comment-8437127
   */
  /* -- Delete this line if you want to use this
  $databases['default']['default']['init_commands'] = array(
    'isolation' => "SET SESSION tx_isolation='READ-COMMITTED'"
  );
  // */