Slow

seems about the same to me.. sorry

It was the object-cache.php causing problems – but I’m not sure what or why.

I’m also having problems with backend being very slow (2.9.2) compared to frontend usage. I use object-cache with memcache on another server. The CPU usage and memory usage are more than good.

But in the backend… WordPress is very slow even to begin responding the first bytes to the client… ?? Anyone also experienced this?

I just solved the problem, disabling any type of cache on administration directly. After these modifications, backend got really, really fast.

In /wp-config.php:

# Cache
if (stristr($_SERVER["SCRIPT_FILENAME"],'/wp-admin')) {
   define('WP_CACHE', false);
} else {
   define('WP_CACHE', true);
   global $memcached_servers;
   $memcached_servers = array('default' => array('memcache-server1:11211', 'memcache-server2:11211'));
}

(Remember to comment any other WP_CACHE definitions in the file, leaving only this code.)

And in /wp-settings.php, around line 336 (WPMU Version 2.9.2)

if ( file_exists(WP_CONTENT_DIR . '/object-cache.php') && (is_admin() == false) ) {
        require_once (WP_CONTENT_DIR . '/object-cache.php');
        $_wp_using_ext_object_cache = true;
} else {
        require_once (ABSPATH . WPINC . '/cache.php');
        $_wp_using_ext_object_cache = false;
}

So if it’s in administration, it never loads the object-cache.php that is necessary for memcached caching. Anything else, it executes normally.

Well, after some days testing this approach, it didn’t work quite as expected. The database cache was constantly out of sync with the real data, so things like comments count and scheduled posts were not working. I reverted back to the original and began using wp-varnish as a cache mechanism, eliminating memcached totally.