Windows XP SP3 runs browsers 13% faster than Windows 7 RTM

In a set of comprehensive Windows Web browser performance tests conducted by Betanews on August 7 -- our first test of browsers running on the final Windows 7 RTM Build 7600 distributed by Microsoft yesterday -- the five major families of browsers tended to run 13% faster on Windows XP Service Pack 3 than on Windows 7, and 29% faster than on Windows Vista Service Pack 2.

That reflects a decline in the speed gap between XP and Win7 of about 1%, from tests conducted comparing XP-based browsers to those running on Windows 7 Release Candidate Build 7100. Some browsers are faster in Windows 7 RTM, although Mozilla Firefox 3.5.2 ran just a tick slower.

Our latest complete round of tests shows Google Chrome 3 continuing to make phenomenal gains with each iteration, with developer channel build 196.2 posting another record Betanews index score of 18.96 in XP, and 16.09 in Win7. In other words, on the XP platform, Chrome 3 performs with the relative horsepower of about 19 Internet Explorer 7 browsers running on Vista SP2. There's good reason to believe Google wants Chrome 3 to run particularly well on the older XP platform, which has enjoyed a huge resurgence as a result of installations on netbooks where Vista would either under-perform or not even fit. Apple's Safari 4 build 530.19 is the next best performer on XP with a 16.16 score.

There are a handful of trends worth pointing out in this latest round:

• Apple Safari is also concentrating on XP, with a big performance gap between its XP score (16.16) and its Windows 7 score (12.58). On Vista, Safari 4 scores a 11.77.
• Opera 10 Beta 2 build 1691 is a speed leader in one and only one heat: page load times. For some reason, with Windows 7, Opera 10 blazes past the others, scoring 4.29 relative to IE7 on Vista on the rendering portion of our test suite, which counts toward 25% of the overall score. Safari 4 is second fastest on Win7 with 4.09, followed by Chrome 3 at 3.86. On Vista, the gap is closer with Opera 10 scoring 3.66 on the rendering test, versus 3.29 on Safari 4 and 3.23 on Chrome 3. But in the same test, Opera 10 crashes and burns on XP, scoring only 2.60 versus 4.33 and 4.46, respectively.
• Firefox may yet rival Chrome and Opera in the page rendering department, as speed gains that at one time were planned for version 3.5.1 now appear to be slated for version 3.6, whose development track has now been code-named "Namoroka." Were the latest preview build of the 3.6 alpha not loaded with error correction code -- if it performed as well in error tracking as does the current "Shiretoko" beta of 3.5.3 -- the 3.6 alpha would post Firefox's first solid index score over 10.0 on the Windows XP platform; as it stands, the 3.6 score is now 9.55 on XP versus 9.94 for the stable 3.5.2, and 9.96 for the beta of 3.5.2.
• The speed gap between Windows 7 and Vista is 17.1%, with Internet Explorer 8 scoring a 2.23 in Win7, reflecting a speed jump that's right in line with our geometrical mean. If you're running IE7 on Vista now, you should see 223% better performance from your browser when you upgrade to IE8 on Win7.