Firefox 3.1: How to Enable the TraceMonkey JavaScript Engine
Contributed by Rob Rogers 
Tagged: Mozilla Firefox 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.
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fastfreddie1959 said on October 16, 2008
Locate the Preference Name javascript.options.jit.chrome.
Locate the Preference Name javascript.options.jit.content.
Neither key exsists in FF 3.1
Rob Rogers said on October 16, 2008
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 said on October 18, 2008
Locate the Preference Name javascript.options.jit.chrome.
Locate the Preference Name javascript.options.jit.content.
Nope! still not in my version 3.03
pearlworm said on October 18, 2008
Okay, downloaded Minefield and found them Thanks
Geoff said on October 19, 2008
Fantabulous feature! Tnx a $M
caffino said on October 20, 2008
how do you download minefield
i looked and nothing showed up
adi said on October 21, 2008
its a tweak for firefox Minefield, not 3.03
kansei said on October 30, 2008
it’s called google. Try “download minefield” it’s all over the first results
dorai said on November 4, 2008
it is good i done it very easily
Trikkk said on November 8, 2008
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 said on December 4, 2008
Google JIT or Tracemonkey
There is no catch
Mallikarjun said on December 5, 2008
FF is not troubling me now ………….Thanks
Ross said on December 9, 2008
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.
nanda said on December 10, 2008
they won’t be in 3.03, this is about 3.1
nagu said on February 20, 2009
8. If things break, remember what you did in #3.
nagu said on February 20, 2009
Minefield Rocks!
Anonymous said on July 12, 2009
OMG! Thank you for the information. It worked GREAT!
Anonymous said on October 7, 2009
i could not find following in about:config.
javascript.options.jit.content.
Travel Trailers said on March 4, 2010
now i know, i thought i will nver get through it… thanks…