Is the database by any chance on a different server than the website? Because unfortunately that configuration really doesn't work very well for concrete5. It runs a pretty hefty number of database calls, so adding network latency to all of those queries slows it down a lot.

Looking at the site, one thing you could do is compress the content with gzip. That will often speed things up quite a bit. All you have to do is add the content described in this post to your root .htaccess:http://www.concrete5.org/community/forums/chat/gzip-and-concrete5/#...

Also make sure you have concrete5's caching enabled, as that can sometimes help quite a bit. You can read about caching here:http://www.concrete5.org/documentation/using-concrete5/dashboard/sy...

EDIT: One other thing, for the gzip stuff to work you need to make sure apache has mod_deflate enabled.

Thanks very much for the good advice.