Photoshop woes after 10.6.5 update

So i've posted on both apple's and adobe's forum for help, but no suggestions worked.

Issue: - Photoshop is taking up huge amounts of CPU (over 100%) working on little file.
-Changes are not showing up in the window, but I can see the thumbnails changing.
-If i zoom in and out 5 or six times, the changes show up in the main window, (but I can't work like that)
-It started happening after the 10.6.5 update.

Things i've done (that I can remember)
-reinstalled combo update (twice)
-Cleared font cache (multiple times)
-reset photoshop (multiple times)
-ran disk utility, Onyx, hardware thing on disk etc. (pretty much every kind of normal trouble shooting tool I know about) -I've been working on macs since 1994...
-I made sure there were no duplicate fonts with Font book. and manually deleted fonts I did not use or thought might be causing issues.
-I had no plug-ins in photoshop at all
-no waccom tablet or similar. Only use magic mouse.

My machine is a unibody late 2008 macbook with 6gb ram and a 3.06 processor. So memory or processor speed should not be an issue.

so i'm open to all suggestions. Only photoshop is messed up as far as I can tell and it started happening since the 10.6.5 update.

Thanks.

paul

Have you tried dropping back to 10.6.4?
There was an update pushed recently of PS5 - what version of PS are you using?