I've been working with Photoshop for 11 years now (since version 6 back in 2000 as a freshman in college). I've used it as a student, as a casual user, and as a professional designer.
For at least the past five years I'd consider myself a power user. Meaning, I can make Photoshop crap the bed if the system I'm using has less than 4 GB of RAM and an SSD. Often the files I work with have more than 400-500 layers, and can sometimes be as large as 1.5 GB+. I've even seen Photoshop use up to 6 GB out of 16 GB on my Mac Pro fairly often (via System Monitor in OS X).
A few years ago back when Adobe still had wonderful tech support (reps based in my own country who actually had a background in the design industry) a very helpful support rep pointed me to an article on the Adobe Knowledge Base (that's what it used to be called anyway) about optimizing performance for Photoshop.
At the time I believe I was using CS3, and the biggest revelations for me was getting a second internal hard drive to set Photoshops scratch disks on, so it didn't compete with the OS for scratch space.
Now, fast forward to Photoshop CS6 and while some of the details have changed a bit, there is still a very helpful article on Adobe's site all about optimizing your system's performance while using Photoshop.
</p>The article is split up into four categories:</p>
- Optimizing your hardware setup
- Specifying Performance preferences in Photoshop
- Tips for improving your workflow habbits in Photoshop
- Optimizing the OS for Photoshop
If you've never read an article about optimizing performance in Photoshop before, I would highly recommend it. There's almost certainly something that will be helpful for you in there.
For me I revisited the article just today because I'm seriously considering a move to a Macbook Air, and I was trying to gauge if I'm going to take much of a performance hit and if there's anything I can do to further optimize my performance in Photoshop.
Turns out, one tip I've overlooked even after having tracked with this PS performance stuff for five years now is watching the Efficiency monitor in Photoshop. Did you know that if it reads 100% Photoshop is currently only using available RAM, but if it reads less than 100% it's using scratch space?
Check it out.