Firefox 3.1: How to Enable the TraceMonkey JavaScript Engine

TraceMonkey is the magic pill that makes the new Firefox much quicker. Unfortunately, the beta version has this feature disabled. By changing the value of a couple of configuration settings, you can easily enable TraceMonkey and enjoy its speedy goodness.

1. Open Firefox.

2. In the Location Bar, input about:config.

3. Click to get past the warning message that appears.

4. Locate the Preference Name javascript.options.jit.chrome.

5. Double-click the preference and change the value to true.

6. Locate the Preference Name javascript.options.jit.content.

7. Double-click the preference and change the value to true.

 

About Rob Rogers

Once a prolific author here on Tech-Recipes, Rob has moved on to greener pastures.
View more articles by Rob Rogers

The Conversation

Follow the reactions below and share your own thoughts.

  • fastfreddie1959

    Locate the Preference Name javascript.options.jit.chrome.
    Locate the Preference Name javascript.options.jit.content.

    Neither key exsists in FF 3.1

    • http://www.tech-recipes.com/ Rob Rogers

      Actually, they do. Go to about:config and input the word javascript into the filter. They will be the 4th and 5th preferences listed.

      • pearlworm

        Locate the Preference Name javascript.options.jit.chrome.
        Locate the Preference Name javascript.options.jit.content.

        Nope! still not in my version 3.03

        • nanda

          they won’t be in 3.03, this is about 3.1

    • adi

      its a tweak for firefox Minefield, not 3.03

  • pearlworm

    Okay, downloaded Minefield and found them Thanks

    • caffino

      how do you download minefield
      i looked and nothing showed up

      • kansei

        it’s called google. Try “download minefield” it’s all over the first results

  • Geoff

    Fantabulous feature! Tnx a $M

  • dorai

    it is good i done it very easily

  • Trikkk

    do you have any technical details or an link about how is this change of speed happening ? I mean, I have enabled both options(the truth is that in 3.1b2pre —– Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1b2pre) Gecko/20081107 Minefield/3.1b2pre, the option:’javascript.options.jit.content.’ is already enabled by default, so just enabled the “….chrome” .I have already seen an important increase at speed, but I need to know how it is achieved.I mean, where’s the catch?

    • Kris

      Google JIT or Tracemonkey

      There is no catch

  • Mallikarjun

    FF is not troubling me now ………….Thanks

  • Ross

    Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2a1pre) Gecko/20081208 Minefield/3.2a1pre

    This doesn’t seem to make a difference for me, tested using sunspider javascript benchmark.

  • http://thaats.blogspot.com nagu

    8. If things break, remember what you did in #3.

  • http://thaats.blogspot.com nagu

    Minefield Rocks!

  • Anonymous

    OMG! Thank you for the information. It worked GREAT!

  • Anonymous

    i could not find following in about:config.

    javascript.options.jit.content.

  • http://www.jrconsumer.com/ Travel Trailers

    now i know, i thought i will nver get through it… thanks…