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What’s new with the Firefox Profiler? (Q3 2022)

As the Perf-Tools team, we are responsible for the Firefox Profiler. This newsletter gives an overview of the new features and improvements we’ve made in the third quarter of 2022.

You can find the previous newsletter here which was about the first half of 2022.

Here are some highlights.

Power tracks on Windows 11 and Apple Silicon

Thanks to the new capabilities in Windows 11 and Apple Silicon, we can now capture the power use of Firefox while profiling. We gather this information into useful power tracks with tooltips showing both the instant power but also the energy in the current ranges:

3 tracks dedicated to the power usage are displayed, including a tooltip on mouse hover showing absolute values.

This can be enabled by using the preset Power from the profiler popup:

Select the "Power" preset using the profiler popup

In October, the work continued to support this feature on Linux and Intel Macs.

Thanks Florian Quèze and Dan Robertson for working on this!

Improvements in the timeline

We’ve been busy improving the timeline (the top part of the profiler analysis UI) to make it easier to use when there are a lot of tracks.

Other changes and fixes

Improvements in the user interface

We also made some small usability changes in other parts of the interface, also with the help of a few contributors.

Importers and non-visible changes

Some features and fixes related to importers were done, especially thanks to a few contributors:

And finally we achieved a few “under the hood” changes:

Contributors in Q3 2022

Lots of awesome people contributed to our codebases both on GitHub and mozilla-central in. We are thankful to all of them! Here’s a list of people who contributed to Firefox Profiler code:

  • Amila Welihinda (amilajack)
  • Bhavya Joshi (Bhavya0304)
  • Florian Quèze (fqueze)
  • Johannes Bechberger (parttimenerd)
  • Julien Wajsberg (julienw)
  • Khairul Azhar Kasmiran (kazarmy)
  • Marc Leclair (MarcLeclair)
  • Markus Stange (mstange)
  • Nazım Can Altınova (canova)
  • Paul Adenot (padenot)

We are also thankful of our localization team:

  • Andreas Pettersson (sv-SE)
  • Artem Polivanchuk (uk)
  • Bund10z (es-CL)
  • Fjoerfoks (fy-NL)
  • Francesco Lodolo (it)
  • Ian Neal (en-GB)
  • Jim Spentzos (el)
  • Luna Jernberg (sv-SE)
  • Marcelo Ghelman (pt-BR)
  • Mark Heijl (nl)
  • Melo46 (ia)
  • Michael Köhler (de)
  • Pin-guang Chen (zh-TW)
  • Théo Chevalier (fr)
  • ZiriSut (kab)
  • ravmn (es-CL)
  • robovoice (de)
  • wxie (zh-CN)
  • Іhor Hordiichuk (uk)
  • 你我皆凡人 (zh-CN)

Our translations happen on Pontoon, and you’re very welcome to contribute, either for an existing or for a new language.

Thanks a lot!


Thanks for reading! If you have any questions or feedback, please feel free to reach out to me on Matrix ( You can also reach out to our team on Firefox Profiler channel on Matrix (

If you profiled something and are puzzled with the profile you captured, we also have the Joy of Profiling ( channel where people share their profiles and get help from the people who are more familiar with the Firefox Profiler. In addition to that, we have the Joy of Profiling Open Sessions where some Firefox Profiler and Performance engineers gather together on a Zoom call to answer questions or analyze the profiles you captured. It’s usually happening every Monday, and you can follow the “Performance Office Hours” calendar to learn more about it.

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