Required require_once rant!

open("/home/rasmus/drupal/index.php", O_RDONLY) = 4
open("/home/rasmus/drupal/includes/bootstrap.inc", O_RDONLY) = 4
open("/home/rasmus/drupal/sites/default/settings.php", O_RDONLY) = 4
open("/home/rasmus/drupal/includes/cache.inc", O_RDONLY) = 4
open("/home/rasmus/drupal/includes/database/database.inc", O_RDONLY) = 4
open("/home/rasmus/drupal/includes/lock.inc", O_RDONLY) = 4
open("/home/rasmus/drupal/includes/database/mysql/database.inc", O_RDONLY) = 4
open("/home/rasmus/drupal/includes/module.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/dblog/dblog.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/overlay/overlay.module", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/session.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/common.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/path.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/theme.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/database/select.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/database/query.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/menu.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/tablesort.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/file.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/stream_wrappers.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/unicode.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/image.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/form.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/mail.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/actions.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/ajax.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/token.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/errors.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/block/block.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/color/color.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/comment/comment.module", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/entity.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/contextual/contextual.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/dashboard/dashboard.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field/field.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field/field.crud.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field/field.default.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field/field.info.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field/field.multilingual.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field/field.attach.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field/field.form.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field/modules/field_sql_storage/field_sql_storage.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field_ui/field_ui.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/file/file.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/file/file.field.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/filter/filter.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/help/help.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/image/image.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/image/image.field.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field/modules/list/list.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/menu/menu.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/node/node.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field/modules/number/number.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field/modules/options/options.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/path/path.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/rdf/rdf.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/search/search.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/shortcut/shortcut.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/system/system.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/taxonomy/taxonomy.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/field/modules/text/text.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/toolbar/toolbar.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/update/update.module", O_RDONLY) = 5
open("/home/rasmus/drupal/modules/user/user.module", O_RDONLY) = 5
open("/home/rasmus/drupal/profiles/standard/standard.profile", O_RDONLY) = 5
open("/home/rasmus/drupal/includes/database/mysql/query.inc", O_RDONLY) = 5
open("/home/rasmus/drupal/themes/engines/phptemplate/phptemplate.engine", O_RDONLY) = 5
open("/home/rasmus/drupal/themes/bartik/template.php", O_RDONLY) = 5
open("/home/rasmus/drupal/misc/feed.png", O_RDONLY) = 5
Why oh why do you feel compelled to use include_once/require_once everywhere?

Paranoid bootstrap code:

<?php
function _drupal_bootstrap_full() {
  $called = &drupal_static(__FUNCTION__);

  if ($called) {
    return;
  }
  $called = 1;
  require_once DRUPAL_ROOT . '/' . variable_get('path_inc', 'includes/path.inc');
  require_once DRUPAL_ROOT . '/includes/theme.inc';
  require_once DRUPAL_ROOT . '/includes/pager.inc';
  require_once DRUPAL_ROOT . '/' . variable_get('menu_inc', 'includes/menu.inc');
  require_once DRUPAL_ROOT . '/includes/tablesort.inc';
  require_once DRUPAL_ROOT . '/includes/file.inc';
  require_once DRUPAL_ROOT . '/includes/unicode.inc';
  require_once DRUPAL_ROOT . '/includes/image.inc';
  require_once DRUPAL_ROOT . '/includes/form.inc';
  require_once DRUPAL_ROOT . '/includes/mail.inc';
  require_once DRUPAL_ROOT . '/includes/actions.inc';
  require_once DRUPAL_ROOT . '/includes/ajax.inc';
  require_once DRUPAL_ROOT . '/includes/token.inc';
  require_once DRUPAL_ROOT . '/includes/errors.inc';

And what's with the DB autoloader?

<?php
function db_autoload($class) {
  static $base_path = '';
  static $checked = array();

  static $files = array(
    'query.inc' => array(
      'QueryPlaceholderInterface',
      'QueryConditionInterface', 'DatabaseCondition',
      'Query', 'DeleteQuery', 'InsertQuery', 'UpdateQuery', 'MergeQuery', 'TruncateQuery',
      'QueryAlterableInterface',
    ),
    'select.inc' => array('QueryAlterableInterface', 'SelectQueryInterface', 'SelectQuery', 
                          'SelectQueryExtender'),
    'database.inc' => array('DatabaseConnection'),
    'log.inc' => array('DatabaseLog'),
    'prefetch.inc' => array('DatabaseStatementPrefetch'),
    'schema.inc' => array('DatabaseSchema'),
  );
Pretty much every Drupal page is going to read from the database, so just load at least query.inc and select.inc on every request. You can autoload the less frequently used things.

Not wild about this either: 


access("/home/rasmus/drupal/sites/sites.php", F_OK) = -1 ENOENT (No such file or directory)
access("/home/rasmus/drupal/sites/drupal/settings.php", F_OK) = -1 ENOENT (No such file or directory)
access("/home/rasmus/drupal/sites/default/settings.php", F_OK) = 0
open("/home/rasmus/drupal/sites/default/settings.php", O_RDONLY) = 4

Which comes from this bootstrap code:

<?php
function conf_path($require_settings = TRUE, $reset = FALSE) {
  $conf = &drupal_static(__FUNCTION__, '');

  if ($conf && !$reset) {
    return $conf;
  }

  $confdir = 'sites';

  $sites = array();
  if (file_exists(DRUPAL_ROOT . '/' . $confdir . '/sites.php')) {
    // This will overwrite $sites with the desired mappings.
    include(DRUPAL_ROOT . '/' . $confdir . '/sites.php');
  }

  $uri = explode('/', $_SERVER['SCRIPT_NAME'] ? $_SERVER['SCRIPT_NAME'] : $_SERVER['SCRIPT_FILENAME']);
  $server = explode('.', implode('.', array_reverse(explode(':', rtrim($_SERVER['HTTP_HOST'], '.')))));
  for ($i = count($uri) - 1; $i > 0; $i--) {
    for ($j = count($server); $j > 0; $j--) {
      $dir = implode('.', array_slice($server, -$j)) . implode('.', array_slice($uri, 0, $i));
      if (isset($sites[$dir]) && file_exists(DRUPAL_ROOT . '/' . $confdir . '/' . $sites[$dir])) {
        $dir = $sites[$dir];
      }
      if (file_exists(DRUPAL_ROOT . '/' . $confdir . '/' . $dir . '/settings.php') || 
          (!$require_settings && file_exists(DRUPAL_ROOT . '/' . $confdir . '/' . $dir))) {
        $conf = "$confdir/$dir";
        return $conf;
      }
    }
  }
  $conf = "$confdir/default";
  return $conf;
}
The easy fix is to just hardcode the conf path and remove all calls to the conf_path() function.

After fixing all these, we shaved off 10ms of latency and gained about 1.5 requests/sec: 

Response time:		        0.15 secs
Transaction rate:	       32.66 trans/sec