it might be easiest to try and reset your preferences before doing too much troubleshooting…
so you don’t unnecessarily delete your preferences, quit ae, then go to users/username/library/preferences/adobe/after effects and pull the folder with the version number (8.0) to the desktop, the restart ae and open a project that was giving you problems and see if it is any better with a fresh set of preferences…
if it is, great, you can go to the preferences and make a few tweaks to try and get things working better… with what you’ve listed about your system, i’d enable multiprocessing. personally, i’d also disable opengl acceleration in the previews pref. i also think that i would leave the memory and cache settings alone for now and i would only enable disk caching if you keep all your media/renders on a drive bus that is separate from your main/boot drive (usually this would mean that all your media/renders are on an external drive, not using the internal drive bus).
if you like running another app or two while ae is open, you might download /throttle. its a little gui script for ae that gives you control over how many processors you want devoted to ae. you could devote 7 to ae leaving one for surfing the cow, or photoshop or something. if that 1 processor isn’t busy, ae will use it for any multithreaded effects, so it’s not really ignored by ae. there is also the manual preference hack to achieve the same result, but the script is easier…
Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW