How to speedup xcode builds without any project modifications?

Question

Last version or XCode (3.2.1) is running very slow on OS X 10.6.

What kinds of tweaks can you do to your Mac in order to speedup Xcode build process.

Answer 1

Disabling code sense indexing can free considerable amounts of memory and CPU in large/complex projects, while speeding up the IDE itself.

Xcode 3

Use Preferences from the app.

Xcode 4

defaults write com.apple.dt.XCode IDEIndexDisable 1