I deleted photoshop preffs and that didn't make any difference and activity monitor says ps is using 564 mb and safari is using 271mb, besides that nothing really.
Other things to consider: is there any network activity (involving Photoshop) that could slow your Mac down? Very unlikely
but just to be sure, does Photoshop run as an Intel application?
You could also try to empty all caches using applications like Onyx. Sometimes, weird issues are linked to fonts, did you install fonts (or applications that install fonts like MS Office).
I'm sorry to say that I'm running out of suggestions. Try to call Adobe support or post in Adobe user to user forum.