Displacement of water in an ocean kills performance

[o11c]

If a single node is placed into the surface-level ocean, that will force a cube up to y=2 and it will wander infinitely, killing performance.

Even subsequently digging holes underwater (if you can do this without drowning due to lag) doesn't help, since any nearby clay will usually fill the holes before the top block happens to float over one.

The only workaround is to build a corral of dirt at y=2 from the nearest shore, trapping it, and then destroying it by building a box around the water and yourself and then filling every internal node so it doesn't have anywhere to displace to.

The problem might be solvable by any of:

1. enabling/disabling displacement on a per-nodetype basis (since it's mostly interesting for lava), or
2. making clay also absorb extra water rather than just add it.
3. somehow disabling displacement just for the ocean directly, or
4. using some other method than clay to keep the sea level fixed. Perhaps replace all y=1 water (or y=2 air?) with a special infinite node instead?