Dunno, just speculating. Generational GCs use the observation that most objects die young. A generational graph store can use the observation that most accesses

Dunno, just speculating. Generational GCs use the observation that most objects die young. A generational graph store can use the observation that most accesses are to new objects—generally true of social graphs. You can move objects that are frequently accessed together into the same region, which some moving GCs do in order to obtain better cache behaviour, or evict infrequently accessed objects to “cold nodes” which you treat as the worst-case slow path. You can prefetch objects that you intend to traverse during the evaluation of a node program. And so on.