Wow, first time seeing a speed run of one of my games, pretty impressive. I honestly hadn't even thought about the speed running possibilities but I'm glad the game holds up for a fun speedrun.
As for the gravity mechanic. It ended coming into play later than planned. Part of it is how cramped the world ended up due to my time-constraints, the other part is the open nature of the game. It's actually possible to enable gravity changing even before either of the other two upgrades as you only need 2 crystals. The jump up to the 'lighthouse' (as I call it) can be done without double jump via a carefully aimed dash through the two orbs lined up diagonally. Though going straight for double jump does seem like it'd be the faster route due to setting you up for a clean sweep of the jewels.