installed memcache, no noticeable improvements I just installed varnish and memcache on my server. Varnish works great but I don't really know how memcache should perform. I can't see any improvements for authenticated users.

I turned on memcache statistics and saw that it is working but I can't see a noticeable improvements in the page loading time.

Any ideas on how I can improve performance for authenticated users for an existing website?

Thanks, M.
I recommend you to try/use Authcache module 

http://drupal.org/project/authcache

Make sure to configure it with memcache by adding the following line in your settings file 

$conf['cache_inc'] = './modules/authcache/api/authcache.inc';