Cool deal: 27" iMac 5K with 1TB Fusion / 24GB mem / Applecare only $1655
Mac Pro Westmere Photoshop Performance: diglloydMedium
Note: Photoshop CS5 on Mac OS X 10.6.4 is highly sensitive to the “max memory usage” setting. Set it at 70%—going higher slows things down substantially.
The diglloydMedium benchmark measures core Photoshop operations, generating a 15.7GB scratch size. Therefore, a machine with 16GB memory will show impaired results; 24GB is preferred.
The 2010 3.33GHz 6-core is the easy winner, but note that it’s barely faster than the 4-core Mac Pro, and with the 12-core 3.33GHz machine far behind.
That the 12-core 3.33Ghz model is 31% slower than the 3.33GHz 6-core model shows just how impaired the Photoshop CS5 code base is.
To use GHz as a comparison, the 12-core 3.33GHz model is running at an equivalent clock speed of 2.5GHz, in comparison to the 6-core 3.33GHz model.
Photoshop CS5 slows down with too many cores; see Why More Cores Are Slower.
CPU core usage
See Monitoring system performance with Activity Monitor. Black areas are idle, red and green are usage.
This is typical Photoshop—less than full use of CPU cores, with about 60% of the computing power squandered on the hexacore Mac Pro. This graph is from 10 iterations.