Reporting a Performance Problem

This article will guide you in reporting a performance problem using the Gecko Profiler extension.

Setting up the Gecko Profiler extension

  1. Download and start the nightly build for your platform. You will have to close all running instance(s) of Firefox before launching nightly.
  2. Nightly is a development version, which may contain bugs, so test with a new profile or back up your data.
  3. Verify that it is running correctly by going to 'About Nightly' by looking for 'nightly' as the update channel (3rd line). The icon should be a blue globe.
  4. Download and install the latest version of the Gecko Profiler extension (once downloaded, drag the .xpi file over your Firefox window).
  5. The profiler extension will show up in the top right of the URL bar as a globe icon (if not, drag it there from the Customize window).
  6. Remember to disable or uninstall the extension if you're not using it.

Using the profiler

  1. Reproduce the performance problem. If possible let the problem manifest itself for 5-10 seconds.
  2. Click on the 'Globe' in the top right and select 'Analyze'. Try to do this within a few seconds from reproducing the performance problem. Only the last few seconds are recorded. If the timeline has a large red block it's a good sign.
    Profiler controls
  3. The data will open in a new tab. There will be a button in the bottom left called 'Share' which will upload this profile and once completed will write out a link. Copy this URL to your clipboard by right clicking and add the profile URL to the bug for your performance problem and/or send it to the appropriate person. Try to give some context about what you were doing when the performance problem arose such as the URL you were viewing and what actions were you doing (ex. scrolling on

Document Tags and Contributors

 Contributors to this page: sirnone, Karlt, Nickolay, Aleksej, Sheppy, bgirard, pdmdn, dbolter
 Last updated by: sirnone,