Windows Vista SP1 (Service Pack 1) is not measurably faster than the original stock edition, a Florida-based developer of performance testing and network metrics software said Monday.

"Microsoft has hinted that SP1 is faster than Vista RTM," said Craig Barth, the CTO at Devil Mountain Software, referring to the release-to-manufacturing version of the operating system. "But we found pretty much nothing measurable. It surprised me as much as it surprised everyone else, but the numbers are the numbers."

Devil Mountain ran its DMS Clarity Studio framework on a laptop Barth described as a "barn burner" -- dual-core processor, dedicated graphics, and either 1GB or 2GB of memory -- to compare performance of the SP1 release candidate that Microsoft released last week with the RTM version that hit general distribution last January. The Vista RTM was not updated with any of the bug fixes, patches or performance packs that Microsoft has pushed through Windows Update since the operating system's debut.

"One gigabyte, 2GB [of memory], it didn't make a difference," said Barth. "SP1 was never more than 1 or 2 percent faster."

The difference between Vista RTM and SP1 on Devil Mountain's Microsoft Office-based test script was "statistically insignificant," Barth said, while a multitasking test panel produced results for SP1 less than 1 percent faster than RTM.

"Our goal wasn't to bash Vista," said Barth. "We've been doing this for a while, we know how to do it, and we tried to be as clinical as possible. But SP1 is not going to be a panacea for any performance problems users have with Vista. If you've been disappointed with the performance of Windows Vista, you're not going to be any happier with SP1."

The bottom line: It's Vista's architecture and feature set -- Barth cited Volume Shadow Copy, Vista's snapshot service, as an example -- not a lack of fine-tuning or bug fixes that makes it perform poorly on PCs that run Windows XP blazingly fast.

Microsoft has touted a pair of performance packs that it has delivered to Vista users via Windows Update and that have also been rolled into SP1. The updates, issued most recently just last week, have included fixes for such performance-related issues as slow waking from power-saving states. Microsoft was not immediately available to comment on the Monday test results.

Barth also said Devil Mountain is kicking off a community-based testing network, dubbed exo.performance.network, that it hopes can grow into an industry metrics resource. Users who register receive access to some of the company's testing scripts and a Web-based portal where results are shared. Some software must be downloaded and installed on the user's PC.