Once among the fastest, Firefox's TraceMonkey JavaScript engine has slipped behind the performance offered by Chrome, Opera, and Safari. In hopes of propelling Firefox into the lead, Mozilla is developing a new JavaScript engine called JägerMonkey.

To accomplish the feat, the outfit is borrowing some code from Apple's WebKit project. Mozilla aims to meld the powerful optimization techniques of TraceMonkey with the efficient native code generator of Apple's JSCore engine. An implementation that could regain lost ground for Firefox in the JavaScript speed wars.

"The reason we're [building JägerMonkey] is that TraceMonkey is very fast for code that traces well, but for code that doesn't trace, we're stuck with the interpreter, which is not fast," explained Mozilla developer David Mandelin. "The JägerMonkey method JIT will provide a much better performance baseline, and tracing will continue to speed us up on code where it applies."

The project is just underway and interested developers can download the code from Mozilla's version control repository.