
Apparently I needed to move the island through another three engines just to be sure.
I drove the same two-minute camera route through current whole-island builds in Godot, Flax and Unreal. On this machine they came out around 65–68, 107–108 and 90–92 frames per second respectively. Those numbers are useful for spotting trouble in each build. They are not a fair engine leaderboard: the materials, terrain, lighting and even the frame clocks still differ.
Godot then handed me a glorious 305 FPS. I looked at the screen and most of the harbour buildings had vanished. Fastest island in the world, provided I don't need the island. That run went straight in the bin.
Unreal is where I'm continuing the game for now. It already has useful game work behind it and the closest version of the look I want. I still need proper streaming tests, fewer hitches and an island that keeps all its buildings in view.

Watch prototype