User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:58.0) Gecko/20100101 Firefox/58.0 Build ID: 20180206200532 Steps to reproduce: I tested both Firefox and Chrome viewing the same Youtube video (just as an example) and compared the "Energy Impact" listed in the Mac OS Activity Monitor. I also tried installing the Profiler add-on to get more information on what Firefox was doing when I browsed a site with streaming video. The latter was suggested by /u/zbraniecki on Reddit's /r/firefox forum Actual results: The Activity Monitor Comparison can be seen here: https://imgur.com/a/Jmgsz The Profiler information can be found here: https://perfht.ml/2EbGLNy Expected results: I would expect that Firefox and Chrome's power usage while watching streaming media would be similar; as it is, Firefox appears to be using twice as much energy by the Activity Monitor's reckoning. Even in longer-term testing I've done over 30-60 minutes, the difference is significant, with Chrome using much less power over time.

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:60.0) Gecko/20100101 Firefox/60.0 Build ID: 20180226230123 I was able to reproduce this issue using a MacBook Pro (early 2015) with the latest Nightly build. There does seem to be a significant difference in energy consumption between Nightly and Chrome. While using Nightly I have seen variation between 90 and 450, and while using Chrome the values are between 80 and 200. I'm not sure if this is Mac specific or not because I don't have a Windows laptop to test this on.

Dan, please close this as a dup of your power usage tracking bug.