what does tracemonkey feel like?

One of our goals with Firefox 3.5 is to help upgrade the web. Over the lifecycle of this release we’ve invested heavily in developer features. One of the features that we’ve invested in is TraceMonkey – a tracing interpreter that turns commonly-run JavaScript code into machine code so that it can run at near-native speeds. We consider it to be both an end user feature because it makes existing web applications faster as well as a developer feature because of the new kinds of applications it enables.

We’re always challenged to try and come up with ways to describe what that means in a way that’s not a dry benchmark. How can we explain what it feels like?

We’ve made a video to help describe both what it means by the numbers, but also shows what it feels like. If you want to try the demo we suggest you try it in both Firefox 3 and Firefox 3.5. It’s something you can really feel.

Sadfaces. Your browser doesn’t support native video. Maybe you can try the .ogv version or the .mp4 version and hope for the best?


  1. morgan

    Hi. Is 64bit tracemonkey likely to be in a point release update or are we going to have to wait till Firefox 4?

    I do notice that some pages are slower in the AMD64 version – google mail/slashdot, etc.

    Since Linux now has had AMD64 Flash plugin (which works much better than the 32bit version even though it is alpha) and a AMD64 version of Sun java plugin more people I know have installed AMD64 versions of Linux.

    Nice work otherwise on Firefox 3.5, Can’t wait to see what future versions bring.

    July 28th, 2009 at 12:18

  2. default

    Is the 64-bit support going to be backported into the 3.5.x branch?

    July 30th, 2009 at 06:40

  3. Paolo

    I just noticed this thread and I realize now why my FF 3.5 doesn’t look any faster than the 3.0 version. Guess what, I’m on Linux 64 bit and I don’t want to install a parallel 32 bit distribution of libraries and plugins. Mozilla has lost some esteem points with me on this issue.

    By the way, not to troll around but to get informed, what are the technical hurdles of designing Tracemonkey from the ground up so that it could be compiled both as a 32 bit and a 64 bit application?

    August 3rd, 2009 at 03:24

  4. foobar

    I’ve experienced the same “lack of speedup”…
    Of course on 64bit Linux.

    So here’s another voice for TraceMonkey 64bit :)

    August 4th, 2009 at 09:16

  5. Ben

    @ Mecki
    Your arguments are valid, but what I think David is saying is that they release a 64-bit version of Firefox 3.5 when 64-bit TraceMonkey is ready, NOT when Firefox.next comes out, which is the CURRENT situation right now. The two situations are very different as we have absolutely no idea when Firefox.next comes out, or whether its going to be 3.6 or 4.0.

    Also the developer mentality that you’re suggesting is exactly what’s causing 64-bit to remain stagnant and “niche”. It’s a vicious cycle, where developers don’t make 64-bit programs because there’s not enough market penetration of 64-bit OS’es, and then end users who see that there aren’t a lot of 64-bit programs hesitate to install 64-bit OS’es. Its an inherently WRONG mentality. Mozilla should at least step up to plate and provide retroactive 64-bit builds of current Firefox releases to get us out of this cycle.

    And you shouldn’t bash on people complaining. Also the fact that you get so annoyed by the amount of complaining just shows that 64-bit isn’t as niche as you make it out to be.

    August 5th, 2009 at 16:21

  6. Yuhong Bao

    “In 10.4 only background processes (like server processes, database processes, and so on) could be 64 bit”
    More correctly, only command-line processes could be 64-bit in 10.4.

    August 17th, 2009 at 17:14

  7. anonymous

    i was searching google wondering why my firefox 3.5 runs at the same speed as 3.0, tried enabling everything-jit in about:config, nightly builds, ubuntu ppa etc, and finally found this post. yeah, it’s 64-bit linux. seems like firefox 3.5 is the only software on my pc which doesn’t support 64-bit cpus, even freaking flash plugin has 64-bit version this days. feels like back at good ol’ 90s.

    capcha says “laughs” but it’s actually sad i think.

    August 31st, 2009 at 09:51

  8. WindPower

    +1 for Tracemonkey on 64-bit. Pretty please?

    August 31st, 2009 at 21:08

  9. default

    Tracemonkey w/ x86_64 is now enabled in Mozilla trunk. I wonder whether we’ll see it in 3.6, would be very cool.

    October 8th, 2009 at 01:44

  10. Paolo

    Great! I’m looking forward to getting it into my browser.
    Thank you guys!

    October 8th, 2009 at 04:49

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