|No such thing as a small change|
First, you should ignore AoH versus HoH, and instead concentrate of array versus hash.
If the 'keys' to your data are integers, contiguous, and smallish (or can be arranged to be smallish by the subtraction of some constant), use an array.
So, 60% faster and 70% less space used. (That's a single specific example, but quite typical.)
Wherever in a nested structure -- be it AoH or HoA or AoHoA .v. HoHoH -- that the keys lend themselves to the use of arrays, your code will benefit from using them in most cases.
With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
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