Remove the 30FPS cap for the PC version and unlink the last few remaining things from framerate such as loading zones and models (there are videos on youtupe of the game running with an unlocked framerate, zones and models load faster and full shadows are faster, apparently those things are locked to the framerate)

They unlinked most of the game from the framerate back when they adjusted fishing speed on the PC, I don't think there's anything preventing them from unlinking the rest except to be "fair" to PS2 players.