How much faster are the 3.06 GHz Core 2 Duo-powered "Late 2009" Aluminum iMac models than the "Early 2009" models?

Please note that all Macs mentioned in this Q&A have been discontinued. The "Late 2009" iMac models were replaced by the "Mid-2010" models on July 27, 2010.

With even a cursory glance at a comparison of the "Late 2009" Aluminum iMac models to the "Early 2009" models it is readily apparent that with the exception of the high-end iMac "Core i5" 2.66 27-Inch (Late 2009) -- which has a "Core i5" quad-core processor -- the remaining "Late 2009" models all have 3.06 GHz "Core 2 Duo" processors and the "Early 2009" models have 2.66 GHz, 2.93 GHz, and 3.06 GHz "Core 2 Duo" processors.

With such similar -- even identical -- processor clock speeds and reduced L2 cache (3 MB rather than 6 MB) in the "Late 2009" Aluminum iMac models, one would expect the 3.06 GHz "Core 2 Duo"-equipped systems to be essentially the same speed as their predecessors. However, the precise performance only can be confirmed by "real world" testing.

Running its Geekbench benchmark, Primate Labs reported that the 3.06 GHz "Core 2 Duo"-powered "Late 2009" models returned a score of 4297, compared to 3628, 3947, and 4131, respectively, for the 2.66 GHz, 2.93 GHz, and 3.06 GHz "Core 2 Duo"-powered "Early 2009" models.

After conducting a series of "real-world" tests, the industry-standard MacWorld, unsurprisingly, determined:

When compared to its predecessors, the speed gains with the new iMacs are marginal at best. The $1199 3.06 GHz 21.5-inch iMac had nice improvements over the 2.66 GHz 20-inch iMac Core 2 Duo (which was $1,199 at its release earlier this year) in our Aperture, Cinebench, Compressor, Pages, and Zip Archive tests. But in some of our tests -- Adobe Photoshop CS4, MathematicaMark 7, and Call of Duty 4 -- the speed increase was small, if there was an increase at all.

Generally speaking, the 27-inch 3.06 GHz iMac had an overall performance that was about the same as the the previous high-end iMac, the 24-inch 3.06 GHz iMac . . . The new 27-inch 3.06 GHz iMac showed slight improvements over the 24-inch 2.93 GHz iMac of the previous generation.

PCMag tested the "Late 2009" iMac models running Windows Vista and came to much the same conclusion as MacWorld:

The new iMac completed the PhotoShop CS4 test in 1:57 running Mac OS X and 1:46 in Vista. This is pretty much the same as the previous iMac's scores (1:57 in OS X, 1:35 in Vista). Scores under two minutes are good for a dual-core system. . . The system is also pretty fast at 3D and day-to-day tasks: It scored 4,862 points at PCMark Vantage and 10,167 points at 3DMark Vantage (both tested in Vista). Last but not least, the system got a 59-second time in our Windows Media Encoder test, which is an excellent score.

Ultimately, the low-end and middle-range "Late 2009" iMac models perform comparably to the middle-range and high-end "Early 2009" iMac models.

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Also see: How much faster are the high-end Core i5/Core i7-powered "Late 2009" Aluminum iMac models than the Core 2 Duo powered models? How much faster are these models than the "Early 2009" models replaced?