A new public BETA called "worldresizer" is now available that includes the dynamic world resizer.
You can find this new option in the "Game Options" menu and allows you to scale the distance between islands to suit your preference. It does not change the physical size of the islands - just their position in the world.
There are various scales all the way up to x4 scale. Sometimes the game will pause for a few seconds when resizing due to geometry etc either being loaded or unloaded from the scene.
You can only scale the world when you are sitting in a Cargo Unload area - so if you're clicking the plus/minus buttons and nothing is happening then this is probably why. This is necessary because I need to have an anchor point (ha ha!) to ensure your boat doesn't end up in the middle of the ocean due to the world scaling around it so you should find your boat moves with the port correctly. The only thing you might notice is the clouds changing position.
World scaling is not currently saved into your save game so it is possible that if you save your game with world scaling active then you could find yourself a long way from an island or, in a worse case scenario, embedded inside an island.
Feedback in the forums on world sizes, island sizes etc always welcome :) As far as I know this is a pretty unique ability for a game like this.
OTHER FIXES
Updated the GPU instancing system so that trees are loaded/unloaded correctly depending on whether the island they are attached to is visible. Should stop bloat if you visit many islands in a single play.
GPU instancing now clears itself on game load. This gets rid of a few "ghost" trees which I don't think existed at run time. This may also have been the root cause of the random GPU crashes (fingers crossed).