Khananaphone found during the Big20 that you can save maybe a second on the final boss by screen-wrapping an attack during the spawn-in. While the boss is flashing he apparently has a hitbox at the back of his sprite.

Between this and the two cycle statues (which may not be RTA viable) you can probably save a couple more seconds in an ideal run. I don't plan to go for it any time soon, so I figured I'd document it before it's forgotten.