Mozilla speeds up Javascript in Firefox 18 – with IonMonkey

Firefox developer David Anderson has released details on his blog about a new JIT (just in time) compiler for processing Javascript which should be included in Firefox 18. The engine called IonMonkey should perform much faster than Mozilla’s current JagerMonkey engine. The developers have added an additional step during compilation.

Currently their engine compiles directly to machine code, while with the new IonMonkey engine the Javascript code is first translated to an intermediate representation which is optimized before its compiled to machine code.

The developer claims that this new technique makes Firefox 18 about 7% faster in Javascript processing than Firefox 17 and even 20% faster than Firefox 15.  Of course we’re interested in how it compares to Google Chrome which is currently best known for its excellent Javascript speed. The website Ghacks thought the same, and benchmarked Firefox 18 against Google Chrome 23.

In a benchmark called Kraken, Firefox 18 outperformed Google Chrome big time, another benchmark, Octane, shows dissapointing results, Firefox 18 scored 8727 points, an improvment of 200 points over Firefox 17. However Google Chrome scored nearly 13000 points in the same test.

If you want to try it out yourself, IonMonkey is enabled by default for the desktop version of Firefox 18, which is currently Firefox Nightly. It will be enabled soon for the mobile version of Firefox as well. A Beta release of Firefox 18 should become available on November 20th.