When you are trying to troubleshoot a site and see that, from a host perspective, nothing is overloaded or in trouble.
Run:
lsof -ni | grep httpd | wc -l
If that number is the same as (or about the same as) MaxClients, and nothing else looks bad, you probably need to employ some caching.
To test, increase maxCilents, and restart apache. If these newly available connections immediately get used, you have found your culprit.
Install Varnish and rejoice
