[[mw:Extension:ImageMetrics]] will be used to collect additional data about image performance and (eventually - not implemented yet) about how users interact with media.

The extension has a similar architecture to NavigationTiming, except it lazy-loads the main script. Currently it consists of a ~300 byte top script which sets up pre-domready event handling, a ¬300-byte bottom script which deals with request sampling, and a ~2K main script which is lazy-loaded when the request is sampled and uses EventLogging to log image load performance data. Currently the scripts are only loaded on file pages, but I intend to change that as more functionality is added.

Version: wmf-deployment
Severity: normal