N4J's a lot slower at tons of common tasks. If you look into its underlying data model, it's clear why. It achieves the speed it does at certain graph-traversal operations by storing its data in such a way that it's highly specialized for those operations—one would expect this to come at a high cost for other operations, and sure enough, it does.

It also doesn't bother with tons of consistency guarantees and such that you (may) get from, say, PostgreSQL. Yet is still slower for many purposes.