No one seems to have a solution. And to say drop complex themes and plugins isn’t helpful. WordPress is wordpress because of the blogging AND themes and plugins, it’s like saying to speed up the car, get rid of the passengers.
I’ve had a look,
- the CPU isn’t burning out at 100%
- the MySQL is simple(the tables don’t contain 10^6 records)
- it is flacky, sometimes fast, often slow
I think the problem is in the PHP, possibly the linking between the site and 3rd party sources. If a third party source (for example http://www.gravatar.com, not saying this is the problem at ALL) has a throttle on access, then the PHP on your site will just sit and wait till the host is resolved.
I would like to know how many 3rd party sites are being requested during an average page load. Is there a slow one?
Another thing which puzzles me is, if you have more than 1 instance of the your WP site running, get the first one to do a task, this one hangs, then get the second one to do the same task, the second one often does is in a blink.
