We had a similar issue until we sailed 2-3 continents away from the Pillar Spawn Island. The farther away it seems we got from our starting island the more prolific Sunken Crypts became. If I was to give someone starting out advice, it would be do not build a massive headquarters on the starting island. Find a meadow that borders or is near multiple biomes. Make sure there is lots of swamp with lots of crypts and a large mountain (or multiple) biome with drakes & golems. Our best bases were at one time dilapidated Draugr villages in meadows along a shoreline. They came with multiple buildings, and repairing them saved us a tonne of resources. They were also on reasonably flat land, so the amount we had to level and terraform was extremely minimal. Doing a lot of terraforming & levelling on what became our main base dropped our framerates so much that we rarely ever go there anymore. Gardening & fending off invasions are extremely frustrating, as movement is way to choppy. We call it Lagwagon Base now.