User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36 Steps to reproduce: 1. Go to any page controlled by a serviceworker. Eg, https://googlechrome.github.io/samples/service-worker/basic/ 2. Go to the serviceworker JS console and type performance.getEntries() Actual results: No data. Same with using PerformanceObserver. Expected results: I want to see "ground truth" entries for these results, since the window.performance numbers should be relative to talking with the serviceworker. For navigations, "request start" and "response end" should be request to the serviceworker starts and when the serviceworker serves the last byte of the response. With serviceworkers installed on firefox, developers only get that view of the window talking to the serviceworker and no info about the network communication itself. It's important to have both views. Also, if NavigationPreload is implemented in Firefox, please make sure that negative numbers are supported for the serviceworker's navigation numbers to cover the case of cold startups.

Yes, this is a known issue. Unfortunately trying to refactor service workers to better support our multiple process architecture is sucking up all our available time at the moment. We want to fix it eventually, though. Thanks for the report.