[Extreme Mixing]

Use Commit. It creates an audio file that becomes a permanent part of the session. Freeze makes a temporary audio file that disappears when you, or someone else un freezes the track. That can be inconvenient if you are not expecting it.

And, yes it can save resources. If you are using, say Trillian for bass, playing back the audio file is a lot less DSP intensive than having the instrument up.

Steve