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Performance and Memory Tools for the Web Platform
David Baron


As developers of a complex C++ application, we often want to improve the speed or the memory usage of our application. We rely on various tools to measure aspects of performance and memory usage so that we know where to focus our efforts at improvement. As Web developers develop increasingly complex applications on the Web, we need to provide them with the equivalent tools so that they can understand and improve the speed and the memory usage of their applications, and so they can provide better feedback to us about performance and memory usage problems within the platform.

Building these tools would also provide infrastructure useful for users who want to answer questions like "Why is Firefox using so much memory right now?" or "Which of the 20 tabs I have open is making Firefox slow?". Giving users the ability to answer these questions will also put some additional pressure on Web authors to write applications efficiently.


  • Discuss requirements for performance and memory usage tools
    • what they should be able to do?
    • which requirements are more important?
    • how big of a barrier to entry is acceptable for using these tools? (e.g., downloading a separate build? downloading debug symbols?)
  • Discuss implementation approaches for performance analysis tools
  • Discuss implementation approaches for memory usage analysis tools
    • in-process or out-of-process?

I'd like to focus particularly on discussing possible architectural approaches for memory debugging tools, since that's something that I think we need to solve, but one I really don't know how to solve. I'd also like to discuss how much overhead we're willing to take in order to properly "blame" performance and memory usage.

Thoughts on requirements

  • ability to categorize memory usage by frame/page/site and by type of allocation (images, JS, DOM nodes, etc.) [dbaron]
    • allows developers to get a better picture of what's going on and how we can improve memory usage
      • a way to get useful data from users who report Firefox using too much memory
    • allows users to "blame" pages in addition to the browser as a whole
      • can lead to feedback to both page authors (page uses too much memory) and browser developers (what page X does shouldn't use this much memory)
  • standard profiling UI for JS [dbaron]
    • venkman UI plus callers/callees?
  • profiling UI that can point out things that we know are issues [dbaron]
    • explain time spent on things like style resolution, layout, etc., relative to what nodes are being laid out (and what JS triggered that work, even if it was asynchronous)
    • highlight thrashing caused by functions requiring flushes
    • highlight the problems that are causing the event queue not to be serviced for a long time (i.e., show the performance problems in the longest events)

Speaking Notes

Speaking Notes