Well...whether it is fastest depends on how fast you get the back cover off.
I think the original question was regarding the pause between the three-finger-reset and when it actually shuts down to restart. Good question, because it wasn't there prior to OS 6. My Bold would restart as soon as the buttons were pressed.
One other thing...the three button salute is a "soft reset", while a battery pull is a "hard reset". I have never seen a good explanation of the difference (I'm not convinced there is one). You can get an app like QuickPull lite to simulate a hard reset without pulling the battery. But the battery pull is definitely a time-honored BB tradition.