Try putting the outgoing animation as a video background on another menu. The transition from one menu to another is usually faster than the transition from menu to timeline.
Be aware that the amount of “black” between timelines depends on the player and how quickly the laser assembly can move and refocus. Better (more expensive) players will cut the seam between timelines down to almost nothing.
Finally, Encore’s preview is worse in this regard than just about any hardware player.
-Jeff