Memcache Slowing Down Drupal
The errors on the stats page are due to an unrelated issue with memcache reporting. I think the problem you have is with the conf setup. I believe it should be like this for a default set up where all tables are mapped to the same bin:

$conf['cache_default_class'] = 'MemCacheDrupal';
$conf['cache_class_cache_form'] = 'DrupalDatabaseCache';
$conf['memcache_servers'] = array(
    'memcache.domain.local:11211' =&gt; 'default'
);

$conf['memcache_key_prefix'] = 's-drupal';


If that doesn't do the trick you can explicitly code the mappings for each table:

$conf['memcache_bins'] = array(
  'cache' =&gt; 'default',
  'cache_filter' =&gt; 'default',
  'cache_menu' =&gt; 'default'
);


etc.