I used nippy originally, then later Java serialization libraries once it became clear optimization was required. I tried using both Redis and RocksDB. The happy

I used nippy originally, then later Java serialization libraries once it became clear optimization was required. I tried using both Redis and RocksDB. The happy case had all but the last layer of nodes sitting in cache in memory (as long as your memory is more than 1/32 of the size of your disk). I think I could do better starting from scratch given what I've learned.