Updated at 2:40 p.m. PDT with more details about Firefox 3.1 features.
On Thursday, Mozilla programmers built TraceMonkey into the latest developer version of the open-source Web browser, and it will appear in the next released test version, which likely will be the first beta of Firefox 3.1, Shaver said. Firefox 3.1 is due in final form by the end of the year, though Mozilla is willing to let the schedule slip a bit, if necessary.
Another illustration of TraceMonkey speed is a video of photo editing. Contrast and brightness adjustments take about 100 milliseconds instead of more than 700.
TraceMonkey is what's called a just-in-time compiler, one type of technology that solves the problem of converting programs written by humans into instructions a computer can understand.
In contrast, some compilers translate the entire program, a burdensome process that involves mapping all possible paths the computer can take through the code and trying to figure out which are most important. Tracing technology, based on the actual execution of the program, concentrates only on the areas that actually occupy the computer.
"It lets us focus our optimization energy on the parts of the program that matter most," Shaver said.
That concentration means that TraceMonkey doesn't require a lot of memory or a slow-loading plug-in, Shaver said. And it also means that it's good for mobile devices, one of Mozilla's main focuses for browser development.
There's still a lot of work to be done in improving Web-based applications, though. Mozilla's next priority is improving the DOM--the document object model elements of Web browsers that are in charge of drawing and manipulating the Web page overall.
Although TraceMonkey currently is built into the new developer version of Firefox 3.1, it's disabled by default to begin with. "We did that because we want to get wider feedback," Shaver said.
Also in Firefox 3.1
Other significant changes will arrive in Firefox 3.1, Shaver said.
Another is the built-in ability to play music encoded with the Ogg Vorbis format and video encoded with the Ogg Theora format. These formats, while not nearly as widely used or as supported as rivals such as MP3, are free from proprietary constraints such as patents, Shaver said, and therefore can be added to an open-source project such as Firefox.
"We're excited to bring unencumbered, truly open-source video to the Web," Shaver said. The support also works on all operating systems Firefox supports.
Mozilla will start encouraging Firefox users more actively to move to the current version soon. In about the next two weeks, Firefox 2 users will start getting messages to upgrade to version 3, Shaver said.
Currently, when copies of Firefox 2 check Mozilla servers to see if there's an update, the servers don't say to move all the way to version 3, so users must manually update.
"We're looking at doing that in the next two weeks," Shaver said. "The majority of users are still on Firefox 2."