How fast is the iMac "Core Duo" compared to the iMac G5? How fast is it compared to the Power Mac G5?

Please note that all systems mentioned in this Q&A have been discontinued.

Apple states that the iMac "Core Duo" is up to "twice as fast" as the iMac G5. This is true with the benchmarks that Apple uses, but not in real-world tests.

The always excellent ArsTechnica has provided an excellent in-depth review of the iMac "Core Duo" 1.83 17-Inch that is well worth reading in its entirety, but in particular regarding the speed of the system, the author states:

I have tested and benchmarked the [iMac "Core Duo" 1.83 17-Inch] against two other machines of relatively recent vintage: a [Power Macintosh G5 2.5 DP] and an [iMac G5/1.8 17"].

Subjectively, using Universal Binary apps on the 'Core Duo' iMac feel a bit faster than the iMac [G5]. It also compares favorably with using the same applications on my [Power Mac G5].

Given that only a small fraction of applications have been released as Universal Binaries. . . [one will] have to deal with Rosetta. [For more information on Rosetta, you may wish to refer to "What is Rosetta? What does it support?" in the "Macintel" Q&A].

Overall, I'm very impressed with Rosetta. Aside from Unreal Tournament 2K4, I've not run into a single application that was unusable on the iMac. Some were definitely slower on the iMac ["Core Duo"] than on the iMac G5. . . For the most part, Rosetta should be more than adequate when it comes to general-purpose office apps, but for the heavy-duty stuff like Photoshop and other CPU-intensive applications, you'll notice a slowdown. Some reportedly won't launch at all, like Final Cut Pro 5 and Logic 7.

In a real-world application test using "Universal" applications, ArsTechnica reports that to convert a 49.9 MB (640x480) QuickTime movie to AVI format, it took roughly seven minutes 49 seconds on the Power Macintosh G5 2.5 DP, nine minutes 57 seconds on the iMac "Core Duo" 1.83 17-Inch and 11 minutes 14 seconds on the iMac G5/1.8 17".

Likewise, converting this same movie to play on an iPod took roughly three minutes 54 seconds on the Power Mac G5, seven minutes eight seconds on the iMac "Core Duo" and seven minutes 43 seconds on the iMac G5.

Using Photoshop optimized for the PowerPC under the "Rosetta" environment, ArsTechnica reports in a series of tests that "as expected, the iMac 'Core Duo' didn't do so hot. . . In looking back at some older benchmarks on file, the performance of the iMac 'Core Duo' seemed to be on par with a [Power Macintosh G4/1.0 "Mirrored Drive Doors"]. That's obviously a step down from the 1.8 GHz G5 in the older iMac, but it goes to show that Photoshop is usable on the iMac 'Core Duo'."

The ArsTechnica article provides a number of other test results and benchmarks that you may be interested in reviewing as well.

In a "First Lab Test" report, MacWorld notes:

Tests do show that the new Intel-based iMac is faster than the iMac G5 when running native applications. However, we found that those improvements are generally much less than what Apple claims is a 2x improvement in speed.

Instead, our tests found the new [iMac "Core Duo"/2.0 20"] takes roughly 10 to 25 percent less time than the iMac [G5] to perform the same native application tasks, albeit with some notable exceptions. (If you'd prefer, that makes the Core Duo iMac 1.1 to 1.3 times as fast.) And we also found that applications that aren't yet Intel-native--which must run using Apple's Rosetta code-translation technology--tend to run half as fast as the same applications running natively on the iMac G5.

For users considering upgrading from an iMac inline with the average upgrade cycle of three to five years, for example, an iMac G3/500 (Indigo) or an iMac G4/700 (Flat-Panel), the performance gains using "Universal" applications would be massive and the performance of PowerPC-based MacOS X applications on an Intel-based iMac would be no slower, and most likely faster, than their existing systems. Users of these systems still would want to be mindful that the iMac "Core Duo" models would not be able to run "Classic" should they continue to be reliant on MacOS 9 applications. For additional information, you may wish to refer to "Can the iMac 'Core Duo/Core 2 Duo' models run MacOS 9/Classic applications?"