Currently, loading up all of the maps in the hydlaa sector in the CB version (temple, dungeon, sewers, tavern, some of the outer roads) use up -all- of my memory, which is still 512MB. I know quite a few people don\'t have this much, and it is for everyone\'s sake that the game isn\'t set to load all maps at once. It\'s not like they\'re very small maps.
Whenever you enter a new region (big area), it unloads all maps, and reloads only the maps necessary for you to keep on moving.