How to

Open the Performance tools

To open the Performance tools:

  • press Shift + F5

  • select “Performance” from the Web Developer submenu in the Firefox Menu (or Tools menu if you display the menu bar or are on OSX)

  • select “Performance” from Tools button, in the Toolbar, if you have one:


Record a profile

To start a new recording, press the stopwatch icon in the Recordings pane. To stop, press it again:


You can also start and stop recording from the Web Console, using console.profile() and console.profileEnd().

Save a profile

To save a profile, click the link labeled “Save” in the Recordings pane:


Load a profile

To load a profile, click “Import…” and choose the file:


Clear all loaded profiles

To clear all loaded profiles, click “Clear”.


If you do this, you’ll lose any loaded profiles that you have not saved.


Select a tool

To switch between the Waterfall, Call Tree, and Flame Chart tools, use the buttons in the toolbar:


Configure markers displayed

To control which markers are shown in the Waterfall, use the button in the toolbar:


Zoom in

To zoom into a slice of the recording, select that slice in the recording overview: