WTF are you talking about?
I have no idea what you're talking about.
Thus, the statement "DPs do not need instant lookup" is incorrect in this context because:
This implementation requires fast lookups for real-time collision detection.
Using memory-mapped files achieves both performance and persistence.
DPs don't need fast lookup. Maybe it's better to take a better look at the general algorithm. In essence:
1. Generate DPs.
2. Detect collisions.
These two steps are independent. There's no need to store anything in RAM, not even the generated DPs. They may come from a worker node, for example, as a file, before being thrown into a high-capacity storage system (which can be in the order of many billions of entries).