Ok, nap is done, I'm refreshed and ready to tackle the problems...

presets - yes, this occured to me as I was drifting off, thanks for reminding. I'm also going to get a fons manager program I used to use so I can load them onl as I need them (i don't recall the name right now, but you could preview them in the viewer, load them or remove them dynamically, and see the effects immediately in photoshop - that was useful). I realized i have more custom patterns than I thought, so i'll start savng those and closing them out when i don't need them. Hopefully tht's the primary issue.

OpenGL: as i stated, I've turned off the opengl. i don't need sleek fancy eyecandy effects, I want functional. Non of the openGL "enhancements" seem to fit my bill for "moe functional than not" considering i have no use whatsoever for the 3d stuff, and the rest of the "it does this with opengl enabled" all appears to be stuff I can liv without just fine. I have done everything within my power to ensure that the gpu options are not and continue to not be accessed by photoshop. That was the main reason for slowdown on 95% of the results i found in the google search, and the first thing I tried.

Lots of layers don't seem the be the issue, i've tested in files with as little as 1 background layer. I originally thought that WAS the issue (600+ layers in one file, woot)

Space shouldn' be an issue either, with a terabyte drive for scratch

The heat issues, possibly. the fan is working ok, it's a variable speed fan, and it cranks up to levels where I can hear it clearly. I've taken apart the machine recently (about 2 weeks ago) and vacuumed the heck out of it to remove dust, so that shouldn't be the issue. Still I need to monitor the temp and see what it's doing, thanks for the suggestions.

I've checked the memory settings, but not the interrupts, I'll take a peek. And the network cable.. tht one will b a bit of a hassle, the back of the machone is not particularly accessible unless all the cables are unplugged so i can emove it - still, worth a try (d'oh, i can unplug the cable from the router end.. )

And backups, good idea. What's the use of a Tb drive if I don't back up

Well, if these don't solve it, I'm downgrading to CS3. My supplier is very understanding and accomodating, so we'll see what happens.

Thanks for th suggestions, I'll let you know how it goes.