Visualizing web page memory use in Firefox

I remixed about:memory using D3 to make a treemap visualization of how loaded URLs are using memory in Firefox.

Load it by clicking the widget on the add-on bar, or Cmd/Ctrl+Shift+Y

This visualization focuses on which web pages are using large amounts of memory – this is not a complete accounting of all memory being used. This doesn’t yet show how much is being used by some of the Firefox internals.

Add-on installation does not require a restart. Only tested on Nightly builds.


Source code

4 Comments on “Visualizing web page memory use in Firefox”

  1. Lozzy says:

    Do the colours represent anything particular? Because I have 3 orange compartments belonging to tabs that aren’t open (, and

    After looking again (no action taken since last checking) the Google translate one seems to have been offloaded, but that still leaves the other 2, along with an ominously large ‘System Principal’.

  2. that looks awesome! I sense that we’re entering an era where web makers will be able to work on minimizing their webapp memory footprint just like desktop app authors do!

    It’s incredible to learn that my gmail uses twice as much memory as my facebook tab…

    One question I have here is how we match the numbers. The entry point for most outsiders is sth like – take a look at Task Manager or Activity Monitor and read sth like: “Firefox process uses 792MB ram”.
    Then he goes to about:memory and it tells him that explicit memory usage is 547MB (there’s sth about resident memory at the bottom that shows 733MB).
    Finally he installs your extension and the sum of all elements gives him ~170MB.

    I believe we need to build in a UI aid (and/or documentation on a wiki) that helps understanding the difference and what is 170MB vs. 792MB reported by the Activity Manager vs. 547MB reported at the top by about:memory.

    Without it evangelizing it will be very hard 😦

  3. yokull says:

    Add-on isn’t available at anymore?

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