Game freezes when loading explorer map

Whenever an explorer map is to load, the game lags for a long time. Try opening a chest that contains a buried treasure explorer map. It lags terribly for a long time, and right-clicking the chest at first seems to do absolutely nothing. Then, when trying to unlock the explorer maps trades for a cartographer, the game lags, then lags even more, then freezes, then crashes.

This is a critical issue!