Non so nulla di PS ma direi che l'articolo è autoesplicativo

Adobe's Comments on CS Performance: Here's comments from Adobe on the CS vs PS 7 performance (and accuracy)

" Hi Mike, I have now heard back from our engineers about the reasons some of the filters in Photoshop CS are slower than in Photoshop 7. The reduced speed is due to fixes and improvements applied to the filters. Smart blur, for example, which takes three times longer than before, used to perform its operation on the composite channel, which could result in artifacts. The filter now runs safely on each individual channel, resulting in the three fold speed decrease.

In some cases, such as with Pointillize and Color Halftone, the filters have had several fixes or improvements applied to them. The problem you see with the PSBench action script is due to the script's use of these improved, and therefore slower, filters.

Filter speed is a standard benchmark for Photoshop, so at first glance it does appear to put Photoshop CS in a bad light. However, when customers understand why the filters are slower, I believe they will accept the slower performance.

Photoshop's speed has increased in other filters, such as Add Noise, De-Interlace, NTSC Colors, Tiles, Diffuse, Shear, and Palette Knife. In some of these filters, performance has increased up to 40%.
Also, many Photoshop operations have become faster, including Scale, Rotate, Undo, blending modes, File > Open, and path and text operations. In some of these features, the speed increase is over 50%.

The testing we perform that compares over 200 Photoshop operations, including filters and other features, shows that Photoshop CS is faster than Photoshop 7.0.1, overall, by approximately 7%.

Even though some filters are slower in Photoshop CS, their accuracy has been improved, and they now can display a larger, more accurate preview. When an action script is based on some of these filters, the script will be slower. On the other hand, many of the features used most commonly by Photoshop users, such as undo, scaling, rotating, and blending, are as fast or faster than in Photoshop 7.
Regards, David Metzger
Technical Support Engineer (Graphics)
Adobe Systems Europe Ltd. "