I am sensing a slowness in Photoshop since upgrading to CS5/6. I'm used to PS being pretty snappy, especially in opening files and I tend to do the same things now as I have for the past 15+ years.
Anyone else notice this on a Mac? I have a 2009 8-core Mac Pro and a 2010 MBPro.
OS X 10.7.4, CS6
Are Photoshop and OS fully updated?
As with all unexplainable Photoshop-problems you might try trashing the prefs (after making sure all customized presets like Actions, Patterns, Brushes etc. have been saved and making a note of the Preferences you’ve changed) by keeping command-alt-shift pressed on starting the program or starting from a new user-account.
System Maintenance (repairing permissions, purging PRAM, running cron-scripts, cleaning caches, etc.) might also be beneficial, Onyx has been recommended for such tasks.
Weeding out bad fonts never seems to be a bad idea, either. (Validate your fonts in Font Book and remove the bad ones.)
If 3rd party plug-ins are installed try disabling them to verify if one of those may be responsible for the problem.
Christoph's advice above to potentially get things working well for you is right on.
But keep in mind you're not alone; scout around the forum and note that there are several recent threads on slow Photoshop operation. One in particular has to do with slowness with deep documents (lots of layers) and with layer thumbnails turned on in the Layers panel, and a second has to do with the Snap To Layers setting enabled.
In addition to the advice above, you might want to try the different Graphics Processor options in the Photoshop - Preferences - Performance menu. Make sure to fully Quit Photoshop after making any change there and before testing.
Europe, Middle East and Africa