Snow Leopard vs. Lion: Performance head-to-head

Despite more than 250 new features, we aren't aware of any fundamental changes in Apple's new OS X Lion operating system that would affect performance after upgrading. It still offers 64-bit processing, and with Apple's tight control over Mac hardware components, there's no reason to anticipate a learning curve like Microsoft's partners had to deal with when Vista upended the Windows driver model.

Still, the version of iTunes that ships with Lion supports 64-bit processing for the first time. We also wonder about any performance impact from Lion's new auto-versioning feature. There's also the question of how well third-party programs will make the transition in these early days, since they might still be awaiting optimization.

With the 3.1GHz 27-inch iMac on hand from our review this past spring, we took the opportunity to see if Lion introduced any major performance variations compared with our Snow Leopard results on the same system.

For the most part, we found only minor speed variations between the two operating systems. Lion seemed a touch slower in our Photoshop CS5 batch processing test, but it also has a similarly small edge in iTunes encoding. We can't explain the variations with certainty, but it seems that iTunes does indeed benefit from the shift to 64-bit support. For Photoshop CS5, which does not yet support Lion's versioning capability, the performance dip could come from background code tied to versioning, or perhaps it's simply an optimization issue.

Although the performance deltas on both iTunes and Photoshop exceed our 5 percent threshold for statistical relevance, neither is that dramatic. At least on our benchmark tests, it appears that Lion will provide the same speedy performance as its predecessor. Have you had a different experience with Lion's performance? Let us know.