UE5 - World Partition - Massive Map Sizes?

I created a 4KM landscape in houdini and imported it into the level of version 5.03, and created a lot of details, the packaging works well.
These days, I’m migrating this level to the 5.1 preview version. I was surprised to find that the command to load cells disappeared, and at the same time my level terrain didn’t load properly. Yes, whenever I load the world in edit mode, it says that memory is exhausted and the editor crashes. It can’t even rebuild the landscape texture.
The same resources lead to completely different results.
I’m not quite sure what’s going on, the data layers asset needs to be rebuilt, or is the reflection of the water in the world causing more consumption?