Quantum Flow Engineering Newsletter #15

Last week many Mozilla developers attended the Mozilla All Hands at San Francisco.  I didn’t attend the All Hands myself but from the activity on Bugzilla it looks like it was a productive week.  🙂  The intention behind the work week this time was to do focused work leveraging the face to face time that people have together with the goal of improving the 57 release.  In the areas that I watch daily these days (mostly Speedometer V2 and [qf:p1] bugs) the focus was really great, and you will see the details in the acknowledgement section at the bottom.  I hope that reflects how the week was for everyone who attended!

There were 26 [qf:p1] bugs fixed during the week, and progress were made on many more others.  A lot of these are tricky bugs often times requiring changes to old or complex code, so this is an impressive number!  There was also some fantastic progress on Speedometer, a lot of improvements landed on the JS engine side, we found a few new issues to work on during measurements, and the work is making progress at a good pace.  Profiling Speedometer has been really interesting, there is so much code that runs under the benchmark that we keep finding new issues as we keep looking at various narrow portions of profiles.  The graphs below show the progress in the last couple of weeks (note the new test runs on PGO builds on the reference hardware!).

Win 8 64-bit (i7-4700HQ) (score went up from about 97 to 102)

Win 8 64-bit (i7-4700HQ)




Score went up from about 68 to 71

Quantum Reference (Windows x64)

One important performance related project that also landed was budget based background timeout throttling.  This is the initial implementation of the heuristic that Chrome shipped for throttling the timeouts running in background tabs based on a budget scheme (which means if a background tab runs too much timers, it will get throttled.)  There is still work remaining to be done before we can enable this feature but but it’s great to see it get to this stage.  This will be another step we are taking to deal with the issue of background tabs that run too many timeouts.

One final note, next week I will be away on vacation, so once again you can expect the next one of these in two weeks!  With that said, now it’s time to acknowledge the help of those of you who contributed to making Firefox faster these past two weeks!  I hope I am not forgetting any names by mistake.

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3 comments on “Quantum Flow Engineering Newsletter #15
  1. Gerd says:

    Really impressive work. Using Nightly, the whole UI feels sooo fast now 🙂 And we’re are talking about differences between Firefox 55 and 56 in my case, that’s just about 6 weeks work…

    Have a nice and deserved vacation 🙂

  2. Ralf says:

    > The graphs below show the progress in the last couple of weeks (note the new test runs on PGO builds on the reference hardware!).

    So what’s the y axis here? And is high or low better? (I kind of assume low is better as that’s where Chrome is, but who knows…)

    • ehsan says:

      The Y axis is the benchmark score, and lower is better (note that the Y axis is inverted, so lower means a higher benchmark score.)