The bug

In a superflat world with soul soil, lava, and blue ice, replacing one blue ice block will cause all the generators to update. They will form in a straight line, preferring negative X, infinitely. The basalt for each generator forms at the same time, causing massive amounts of server lag. The updates are only stopped by unloaded chunks (not the worldborder, unlike cobblestone generators) and cause a recursive stacktrace to be printed.