U need to disable autosave mode. In autosave mode u lost 3 seconds after each song you played before, and around 6 second for saving before battle round.

alt+tab trick can be made by using 3dAnalyzer with active checkbox on "windowed mode". After the guitar neck disappears you can use alt+tab for skip animation of "You Rock" . It can be used before battle, after battle, after u choose song to play.