Adobe CS 4 (in particular Photoshop) on an iMac

My partner has just upgraded her work Mac Pro and her home iMac to OS X 10.5.x, and Adobe CS 2 suite to CS 4. All Mac OS and CS4 updates are applied. On her work machine it all works fine, no problems.

On her home machine, when she uses the retouch tool in Photoshop (to say smooth out a blemish in an image by using the surrounding colours) the changes she is making do not appear on the screen until she lets go of the tool. This makes it impossible to do serious work in PS as you can’t see where you’ve already done and what’s left to do. There also was a problem where the screen would go black for a second after that same operation, but we solved that by turning off a GPU option in the PS Performance menu.

The iMac is about 2 years old, dual core, 2.18ghz, 2gb memory, an nVidia 7800 or 7600 video card (I forget exactly). Looking at memory, scratch file and CPU usage the machine is not maxing out anywhere, indeed the issue happens even when working on a small file of say 50k or so. PS’s memory usage doesn’t get over 1gb and the scratch file is not in use while she’s doing this. Changing layers and history settings in PS made no difference either.

It’s tempting to say the problem is that the iMac just isn’t up to it, but I’m not seeing any actual evidence of that in any measurement or monitoring tool. There are certainly posts on Adobe and other forums claiming that the problem is that the iMac just isn’t up to it, but I don’t see why - it’s not that weedy, and hads no such problem with the same image files under CS 2.

So I’m wondering if anyone else has come across anything like this, and can validate that the problem which won’t be fixed except by a hardware upgrade, or has any other ideas in the Mac OS or CS or PS itself that might help? What chance is there that upgrading to the most powerful current iMac version would help? It’s only 3.08 ghz and an NVIDIA GeForce 8800 GS so I don’t see that’s liable to make a huge difference. Certainly we don’t want to upgrade unless it’s sure to fix this problem.

Thanks to anyone who has experience in this area!

I don’t have a solution, but as a data point, I have what’s probably an identical machine with CS4 on it, same memory, and my card is the low-end 7300 (the better card would be the 7600). I also use the retouch tool extensively, and it works perfectly fine on its own.

I will add that I always do clean installs of OS’s and major applications, though, rather than going through upgrades.

db monkeys fixed

Hmm, well OK, thanks for that. I’m not sure where that leaves us; perhaps a complete wipe and reinstall, do you think?

I dug this performance-optimization guide for Photoshop CS4 out of Adobe’s website. This looks like it might be relevant:

Yes, thanks, the GPU option change I mentioned above we got out of their website too. They do mention similar-sounding issues with the nVidia 7300gt

but I don’t think that’s what she has. And Balthisar seems to have that card and doesn’t have the problem. All quite odd.

A minor update on this: I said in the OP that the problem happened with the retouch tool, but I’ve since learned that covers several tools; in fact it only happens with the Clone Stamp Tool. You pick up a colour/texture with it and start spreading it elsewhere, but you can’t see the results until you let go of the mouse button and boom the changes all appear at once. We tried it on my Mac Pro and it works perfectly fine so it’s definitely this machine and CS4 together.

Balthisar, any chance you could confirm with that exact tool? Thanks!

Alas, that will be be impossible. My machine has been declared unrepairable (graphics card problem!), and I’ll be getting a shiny, new aluminum model as a replacement. The only downside to AppleCare is that they’re slooooooow.

My 17" Mac has an ATI card of a decidely lower class; I could try it on that, but now the configurations won’t match.