I'll concede on the hot cache suggestion. Storing the files lexicographically is an interesting thing - it means that grep/find (or anything else that reads through the files/directories in order) would perform well. But this makes the test to some extent contrived to specifically run fast on this particular system.

I do agree that this kind of filesystem mechanism should give good performance benefits. But in the general case they won't be quite as fantastic as these benchmarks make out.