Snappy #37

Highlights from meeting notes for today:

  • Tim Taubert worked on Firefox UI speedups
  • Lots of improvements to the profiler from Benoit Girard
  • More incremental GC work from Jon Coppeard
  • Vladan Djeric got all of the security reviews and should be able to land Nicholas Chaim’s fix for networked certificate validation: bug 726125

We spent most of the meeting discussing bug bug 784512. According several data sources Firefox 15 Beta loads pages slower than 14. Occasionally problems squeeze past our performance testing + telemetry infrastructure, this looks like one of these times. Unfortunately, it’s quite hard to reduce a few noisy signals to a concrete performance problem. If you can reproduce a performance regression to do with loading webpages/games/etc in FF15 vs FF14, please leave a comment.


Thanks for the great comments on my previous snappy updates. Bug 783755 should take care of the new cache size pref not sticking. Bug 718910 on hiding Cache directory from Spotlight is making progress too.

Commenter, kumalos, reported a tab switching regression and posted a profile recorded with our profiler as evidence. This proved to be an example of bug 783748, and lead us to identify a previously unknown issue in bug 784756. Constructive feedback like this is one of the main reasons I blog.

I highly encourage users interested in improving Firefox performance to use Nightly builds and report bugs with profiler traces attached.

Shutdown Times

I’ll end with our latest Telemetry data point. This one took a while to get right, but we finally track our shutdown speed.


  1. “I highly encourage users interested in improving Firefox performance to use Nightly builds and report bugs with profiler traces attached.”

    Is there a page that clearly explains, step by step, how to do this?

  2. Any ETA as to suppersnappy landing in nightly firefox?. Can you give your most accurate estimate as to how close it is to landing in nightly firefox.


  3. Also how close is K90 to completion or at least allowing IGC to be enabled.

  4. @linux_op
    Incremental GC is default enabled in Firefox 16 which will move to Beta Channel on August 28. To be precise it is Incremental Marking GC, while Incremental Sweep GC for Atoms table, shapes and one other thing landed already in Firefox 17 which is still under development so can’t say which more can or will land in it.

  5. Usually, even with simple stuff, in WebGL the browser seems to use too much power, and the gpu fans goes high. Do you think I can use the profiler to investigate this the next time it happens?

  6. @AV We’ve investigated measuring power usage in the past for CPU see my blog post:

    A similar experiment could be done for the GPU if we have a way to get data about the power usage of the GPU. But there’s nothing out of the box for either since it’s very platform and hardware dependent so we haven’t invested resources into shipping that.

    For now the focus is to optimize the performance which generally means using less power (esp. on mobile).

  7. on the IE9 maze solver page, with a 40×40 maze, just moving the mouse on the maze(maze is at idle, not solving) causes HUGE janks. My profile with latest FF17 nightly. I am just moving the mouse inside the maze.

  8. @mayank:
    Did you report a bug with that profile trace attached?