Firefox 3 promises to be a speed-monster

March 6, 2008 at 13:33 Leave a comment

Fast(er) Firefox

The latest nightly builds of Mozilla Firefox 3 are now being built with Profile Guided Optimization (PGO), and tests confirmed that Firefox 3.0 is now the fastest browser on the earth and more than 30% faster in JavaScript tests than the latest Opera Beta (9.5.9807)…

The figures reports the results of the SunSpider JavaScript Benchmark test, used for each of the different browsers. All of the tests below were performed on the same Windows machine, and the Firefox 3 nightly builds definitely came out on top. Here are the results sorted from best to worst (each one is hyperlinked to the full stats):

  1. Firefox 3 Nightly (PGO Optimized): 7.263ms
  2. Firefox 3 Nightly (02/25/2008 build): 8.219ms
  3. Opera 9.5.9807 Beta: 10.824ms
  4. Firefox 3 Beta 3: 16.080ms
  5. Safari 3.0.4 Beta: 18.012ms
  6. Firefox 29.376ms
  7. Internet Explorer 7: 72.375ms

So what is Profile Guided Optimization?

When building (compiling) Firefox, a set of tests are run and the data from these tests are used to optimize the compiled code. The data from the tests enables the compiler to aggressively optimize code in Firefox. The data represents how the program is likely to perform in a production environment. Basically, it runs the Firefox code to see what functions get used the most and optimizes the final code around that data.

Profile-guided optimization is a relatively new feature in both GCC and Visual C++ that improves the quality of generated code.

IE already doing this

IE7 was build with Profile-Guided Optimizations and gained a 8% performance improvement with no additional code change.

For more information about Profile-Guided Optimizations:
Profile-Guided Optimizations in Microsoft Visual C++
Building with Profile-Guided Optimization


Sources: and

Entry filed under: Firefox & Thunderbird, Technology. Tags: , , , , , .

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