So it occurs to me...

The optimal route for Seaside Drive is that you lose a life on purpose for each of stages 1-3, since the minigame you get for a flawless victory is a major time loss, and then you have to beat stage 4 with 0 lives remaining

True. If I might add in relation to the Cherry Route: since getting cherry in SSDr requires 300,000 score, there's a lot of interesting optimization relating to getting juuuuuuuuust enough points to get the cherry Req. Meaning, You can throw a life away if it would save time to do so and not impact your score enough, OR Not hit all the Breakout Bricks in the Bonus Stage intentionally to end it early, or miss some kills intentionally if it allows you to DPS something that WILL save time by doing so. Also At minimum you need to do 2 Bonus stages, I reckon, to get enough points to get to 260,000, the minimum needed + Final Boss (40,000 points) to get cherry. Methinks