I've been benchmarking a Drupal 7 site and I've found apache is up to four times slower in terms of page execution than an Nginx set up I've created. As it's page execution time my understanding is that no other requests will be made for page assets until after its execution is complete so it's unlikely to be caused by how multiple requests are handled (I should also mention that these are test servers only being accessed by myself).
I tried setting up PHP-FPM to work with apache to rule it out as a possible factor but it only had an effect on the page execution time of around 2%.
Each server is running Ubuntu 11.10 with the software coming from the PPAs and only the minimum amount of configuration changes after install to get the servers showing drupal.
As far as I know this is the reverse of what I should be expecting with this setup. Apache should have an advantage as it's not having to call out to an external service but instead I'm seeing results massively skewed in favor of nginx.
Is there any explanation for the results I'm seeing? Can someone provide tips for how I might go about determining the cause?