ANSWER:

I think what counts in here is the MySQL-config as well as how well you’ve worked on sending the right caching-headers for static content.
In fact your benchmark is telling you not what you were asking for, since it is only focused on the PHP-scripts + MySQL-queries. However a site-request is more.

Your benchmark does not include requests for

• images
• JavaScript-files
• CSS-files
• AJAX-calls (if relevant)

I recommend you to look for slow and inefficient queries as well.
You could start here:
MySQL’s slow query log.

You should also keep in mind that “ab” takes only one specifig page-request into account. So if your server is well configured, you are hitting caches from the 2nd request on…

by Ems from http://serverfault.com/questions/390651