The first optimization I found was in stage 17. If you have played the stage, you will know that the standard route is to use both star orbs in order to have enough launch power to cross all the gaps. However, this causes a slight slowdown in the progression in the stage due to a velocity orb. In this optimization you can skip the second star orb entirely and make the stage go slightly quicker. Have a look.

Another optimization I located was in stage 22. Similar to the optimization on stage 17, this movement speeds up the pace of the stage by decreasing the amount of orbs you have to use. Have a look.