I often find myself wanting to open Xcode and do a little coding on international flights and while I'm away from power, but it's a quick way to empty my MacBook Pro's battery.
What settings do you use to preserve battery life while running Xcode?
Predictive compilation automatically disables itself when running on battery.
If you have a dual-core machine,
defaults write com.apple.Xcode XCMaxNumberOfDistributedTasks 1
compiles one file at a time (instead of one on each core of your dual-core CPU) which may result in some savings.