Todd also provides addition links to relevant resources supporting this wide-ranging update to performance tweaking. He says "The most comprehensive place to find information on improving performance in After Effects is the Improving performance page in After Effects Help. Much of what is listed above can also be found there, plus much more."
Of particular interest for Final Cut users is this from AE Help:
Note: Additional project considerations were discussed by Mark Christiansen in How to Optimize Projects in After Effects CS5.
Update: via @AdobeAE, not exactly related but good for reference is a thread on the Adobe Forums, What PC to build?.