Extension:NavigationTiming

The NavigationTiming extension allows logging perceived latency measurements, exposed by browsers as part of the proposed Navigation Timing API, which «defines an interface for web applications to access timing information related to navigation and elements».

What data is logged?

 * See the NavigationTiming JSON EventLogging schema.
 * Browsers accounting to about 11 % of WMF's requests (as of April 2013) are not supported.

How is the information used?
Engineers at the Wikimedia Foundation intend to use this data to assess the impact (positive and negative) of changes to code or server configuration, and thus to help guide ongoing work on site performance.

Additional resources

 * Navigation Timing: draft specification from the W3C
 * performance.timing object: simplified descriptions of the measurements available.
 * Measuring Page Load Speed with Navigation Timing
 * Wikimedia Stats: Frontend Page Load Timing