First Look: Benchmarks: Rosetta apps bolstered by OS X update

Intel-native versions of Adobe Photoshop and Microsoft Office are still a ways off. But Mac users running these and other programs via Apple’s Rosetta emulation technology on their Intel-based Macs have gotten a significant performance boost from Mac OS X 10.4.8. Macworld Lab tests found improvements in the performance of some non-Intel-native apps on systems running September’s OS X update—with some systems seeing their performance jump by more than 30 percent.

Some background is in order. Apple unveiled its first Intel-based hardware offerings at last January’s Macworld Expo, well ahead of schedule. The only problem: Intel-based hardware arrived before many programs had been rewritten for compatibility with the new processors.

To ensure as seamless a transition as possible, Apple developed an emulation technology called Rosetta that allowed all but a few PowerPC-based programs to run on Intel machines—but with a noticeable performance hit. So while a program rewritten to feature Intel-native compatibility might run faster on a MacBook Pro or Core Duo-based iMac than it would on a comparable PowerPC-based machine, applications running via Rosetta typically ran slower— much slower for particularly processor-intensive programs such as Photoshop.

As an example, take a gander at some of our earliest Intel benchmarks, such as this look at how applications ran in Rosetta on the original Core Duo iMacs. All of those tests back in January found that PowerPC applications ran on that iMac at less than half their native speed.

What changed

Ah, but back in the present day, things have improved dramatically since OS X 10.4.8’s arrival. We first noticed a change as we ran benchmarks on the new MacBook Pro Core Duos last week: Intel-based systems saw dramatic gains in Photoshop and Office tests, enough to bump up Speedmark scores by a couple of points. More in-depth testing found speed improvements in both Word and Photoshop ranging from 3 percent to 36 percent. Photoshop numbers saw the biggest jumps, especially on the Mac Pro/Quad 2.66GHz Xeon.

Rosetta Improvements in OS X 10.4.8

10.4.6/7 10.4.8 10.4.6/7 10.4.8
Adobe Photoshop CS2 Suite Adobe Photoshop CS2 Suite Percentage Improvement Microsoft Word Scroll Microsoft Word Scroll Percentage Improvement
24-inch iMac Core 2 Duo/2.16GHz 1:55 1:15 35 percent 1:26 1:16 12 percent
15-inch MacBook Pro Core Duo/2.16GHz 2:32 1:40 34 percent 1:59 1:55 3 percent
Mac Pro Quad Xeon/2.66GHz 1:25 0:54 36 percent 1:12 1:07 7 percent
Power Macintosh Quad G5/2.5 GHz 0:45 0:46 (-2 percent) 0:35 0:36 (-3 percent)
iMac G5/2GHz 1:15 1:15 No change 0:57 0:58 (-2 percent)
<Better <Better >Better <Better <Better >Better

Best results in bold. Reference system in italics .

All scores are in minutes:seconds. All tests run with 1GB of RAM. The Photoshop Suite test is a set of 14 scripted tasks using a 50MB file. Photoshop’s memory was set to 70 percent and History was set to Minimum. We recorded the amount of time it took to scroll through a 500 Page Word document—MACWORLD LAB TESTING BY JAMES GALBRAITH, BRIAN CHEN, AND JERRY JUNG

Before the OS X 10.4.8 update, a 2GHz iMac G5 beat the 2.66GHz Quad-Core Mac Pro at both the Photoshop and Word Scroll tests. After the update, the Photoshop numbers looked much more respectable, with the Mac Pro outpacing the iMac G5 by 28 percent in the Photoshop test. What’s more, the 2.16GHz iMac Core 2 Duo closing the speed gap enjoyed by its G5 counterpart from 35 percent to a dead even finish. Still, even after the OS X 10.4.8 update, the G5s wiped the floor with the Intel-based Macs on the Word test.

So what accounts for these performance gains? Apple’s release notes indicate that OS X 10.4.8 “improves the accuracy of Rosetta numerics and addresses Altivec translation issues on Intel-based Macs,” but offer few other details. And while those words may not mean a lot to you, the performance gains they are responsible for (especially in Photoshop) can make the time spent waiting for your favorite PowerPC application to go Universal a lot more productive.

[ James Galbraith is Macworld Lab’s director. ]

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