This is a simple one, but like remembering to backup all your data daily (you do, don't you?), it's sometimes forgotten, and then it insidiously slows down your CPU bit-by-bit. Yup, we're talking about Garage Band's very user-friendly automation feature. Once you feel you have the automation as perfect as you might ever want on a specific track, be sure to lock the track. That's done simply by clicking on the little lock icon, which is next to the last on the right in the line of icons under the Instrument's name. When automation is active, a blue button is lit. This could be something as simple as changing the volume, or as complex as the speed of the filter sweep you've assigned to the track. What's nice is that this is a non-destructive edit, so if you click on the blue button again, the automation is turned off and you can make changes. When you're through, you may then lock it once more by simply clicking on the blue button again. Earlier versions of Garage Band did not allow for more than automated volume and panning. But the latest version (in iLife '08) lets you automate many functions, like echo and rotary speaker speeds, visual EQ, and much more. When you click on the disclosure triangle (the last small icon under the name) you'll see the "Add Automation" list. Just click on the ones you want to work on, then click OK.