Use default php-fpm port
Use a separate wordpress user on the system
Add installation of WP Super Cache cli
Run more commands as wordpress user
Install wp-cli as .phar. Don't install Cache command
Configure apt sources to include mirrors mechanism

US package servers were configured, installation were sometimes
very slow.
Adding a jmeter performance test
Improving jmeter test

Using Stepping Thread Group and better graphs
Changing connection details to php5-fpm

On Raspbian, php5-fpm listens on a different connection.
Removing varnish

The Raspbian binaries for varnishd keep segfaulting. Tests on a
different machine suggest that the advantage over WP-Super-Cache is
marginal, so let's lose the additional complexity.