- cut down on in heap memory usage by aggregating cache maps into
  the common index and use String objects in place of DN objects.

- persistent state save/restore speed up and reduced in heap mem
  consumption due to the common index usage with JE serializable
  objects only.

- lock re-shuffling to improve concurrency when priming/updating.

- use JE no locking mode to improve concurrency and keep default
  JE properties in place instead of optimizing for tmpFS space.