by James Galbraith, Macworld.com  

Last month’s release of Microsoft Office 2008 not only introduced new features to the widely used Mac productivity suite but also delivered a version of Office that runs natively on Intel-based Macs. While Office 2004 would work on a Mac powered by an Intel processor, it required the Rosetta translation technology to do so. For many applications, running under Rosetta meant a performance hit, so Intel-based Mac owners were understandably eager to see what kind of performance gains the native version of Office might yield.

We’ve already reviewed the features and enhancements in Word 2008 (), Excel 2008 (), PowerPoint 2008 (), and Entourage 2008 (). But what about the performance of the Office 2008 update?

Macworld Lab has completed some benchmark testing for the shipping version of Office 2008. And we’ve found that the new release improves upon the performance of Office 2004 when running on an Intel-based Mac. However, Mac users still with PowerPC-based machines are in for more of a mixed bag—Office 2008 handles some tasks more quickly than Office 2004, but tasks run more slowly on Macs with PowerPC processors.

Our tests involved a 4-core, 2.5GHz Power Mac G5 and a four-core, 2.66GHz Mac Pro. Both machines ran OS X 10.5.1 and had 2GB of RAM. We ran a series of tests using Office 2004, and then repeated the same tests with Office 2008.

The first test we ran required opening 50 worksheets in Excel. In Excel 2004, the Power PC-based Power Mac G5 was the clear winner, finishing the job in half the time of the 2.66GHz Mac Pro. Once we upgraded to Excel 2008, the Mac Pro beat the Power Mac. However, the improvement wasn’t necessarily the result of a massive speed gain—the Intel-based Mac finished the task 2 seconds faster with Excel 2008 than it did with the 2004 version. Rather, the Mac Pro finished on top because the new version of Excel ran this test significantly slower than Excel 2004 on the PowerPC-based Mac.

This same scenario played out again when we tested scrolling through a document in Word. The Mac Pro sped up a little when upgrading from Word 2004 to Word 2008, but the Power Mac performed much slower with the new version. A second Word test, a find-and-replace operation, turned out to be better news for 2008 upgraders. In that test, the Mac Pro still lagged behind the Power Mac in Word 2004, but both sped up impressively in 2008, with the Mac Pro finishing ahead of the Power Mac by 25 seconds.

Our fourth test, using Entourage to download mail, showed improvements for both the PowerPC- and Intel-based machines after upgrading to the 2008 version of the e-mail, contact, and task manager. However, the Intel-based Mac Pro saw the greatest gain, improving its time by 45 percent to the Power Mac’s 6-percent gain. As a result, the Mac Pro now handles the Entourage task faster than its PowerPC-based counterpart does.

We attempted to run startup tests, but the results were very erratic. For example, Word 2008 startup times varied between 4 and 13 seconds, while it took Word 2004 between 6 and 12 seconds to launch on our 2.66GHz Mac Pro .

It’s probably true that most people give more weight to feature enhancements than performance when it comes to upgrading business software. That said, our basic tests show that there can be some performance benefit for Intel-based Mac users making the move to Office 2008. For PowerPC owners, though, unless the feature enhancements in 2008 are compelling, upgrading may actually slow you down.

[James Galbraith is Macworld Lab’s director.]