Code review comment for lp:~stub/launchpad/page-performance-report

We want to make slow pages faster. At the moment we do this by optimizing test pages, but we really have no idea if we have made other pages slower. When we optimize, we need to ensure the system improves overall rather than playing whack a mole, speeding up some pages while causing others to timeout.

This hasn't been a genuine problem so far, but we want to evaluate using memcache. memcache is unusual in that it will slow down the initial page renderings due to overhead in stuffing data into the caches, and speed up repeat renderings. This branch is to provide us with tools to confirm if our experiments succeeded or failed.

The reporting tool is basic, but meets our initial needs in the current state. I'll probably tweak it some more, but the reason to land this branch now is for the extra information the publication machinery is emitting to the Zope trace log. Once this is landed, we can turn on the logging on one of the edge servers and start to get some real data to analyze.