I use this mod in conjunction with the Island biomes one to build floating cities, however I have discovered that when a sea creature that Island Biomes adds (boomwhales, sharks etc.) goes manhunter the game slows to a crawl until the creature is dead because the bridges seem to interfere with their pathfinding.

The easiest solution is to just pause the game which returns it to normal speed and then enable devmode and delete the offending animal with the destroy command.