I noticed this the other day when doing the singing faces tutorial... i did the faces and hit render... it took almost 17 minutes to render the 3 singing faces. Once i saved it and it had a valid file name renders were under 10 seconds... I assume its a unknown file name on every frame of the render having to wait for a timeout then next frame unknown file name wait for timeout etc.
Edit... quick possible workaround... have them name the sequence when they create it (new sequence from menu ----> sequence name pop up ----> existing new sequence flow (animation or musical) etc. And once done is clicked as its pulling up the sequence it saves it.