Photoshop CS5 Laggy on High Spec MBP

[Always Red]

I have a Macbook Pro (2.2 i7, 8gb RAM) that lags and beachballs when working in Photoshop CS5 on files that aren't even that big (about 100mb).
Running Lion. System rebuilt not long ago.

Thoughts?

 

[maflynn]

I've not noticed any performance issues with CS5 on my rMBP. Are you just noticing the issues now, i.e., it was fast but its slowing down?

 

[Always Red]

Originally it was fine, but more recently it has started slowing down. Was laggy prior to rebuild and continued after.