Intel iMac Core Duo fast but not that fast, says Macworld

Macworld has been timing a 2GHz iMac Core Duo and comparing it with a 2.1GHz iMac G5 and reckons "the gains don't match Apple's claims". It says:

Unfortunately, our tests suggest that the remarkable results of Apple's published tests aren't reflected in most of the real-world applications we tested. Based on our initial tests, the new Core-Duo-based iMac seems to be 10 to 20% percent faster than its predecessor when it comes to native applications, with some select tasks showing improvement above and beyond that.

Performance of non-native applications run via Rosetta may disappoint. Macworld says:

We tested three different non-native applications on the Intel-based iMac, and compared the results to the iMac G5. All of the tests showed that PowerPC applications run on the new iMac at less than half their native speed. Our standard Microsoft Word scrolling test ran at 48% of the speed it ran on the iMac G5; our standard battery of 14 Photoshop CS tasks ran at 45% of the G5's speed; an MP3 encode using the non-native iTunes 6.0.1 ran at 34% of the speed.