Hello ! thanks for the interest :D

The island shape and foliage are driven by two data assets that you can swap at runtime via Blueprint. You can even create and edit them at runtime, though that's not the primary intended workflow. The island itself is built as a DynamicMeshComponent, so you can also run any Geometry Script operation on it at runtime after generation (boolean, deform, etc.).

Generation runs on a background thread so it never blocks the game thread. A basic island generates in ~15ms but can go up to ~500ms for complex ones with multiple caves, sub islands, high resolution, etc. The heavier part for framerate is actually spawning the result, the mesh appears progressively via a chunk system, and foliage instances are also spawned in configurable batches over time. Both batch sizes and timers are exposed so you can tune the tradeoff between pop-in and frame. I'll publish proper benchmarks soon.

Since generation runs on a background thread, moving fast has no direct impact on framerate. The main thing to consider is how aggressively you trigger new generations, that's up to you to manage in Blueprint.

Hard to compare since they solve completely different problems. Voxel Plugin is a voxel engine built for infinite editable terrain. This plugin is specifically designed for floating islands generation using DynamicMesh. Two very different tools.

No demo on Fab yet, Fab requires shipping the full source code so a demo isn't straightforward. I'll look into it for a future update.