Array vs. Hash (newbie perlguts)

[perchance]

I have come into a situation where I am holding a hash of arrays, with a set (and small) number of elements in the list. The key to the hash is an integer of a reasonable size, and what I was wondering was, would it rather be cheaper memory-wise to hold the information as:

• a) Three or four seperate hashes.
• b) A half-empty array of arrays.

I know there might not be absolute answers, but it seems to me the internal implementation must have some clear tendencies, and I am pressed for memory...

thanks in advans,
perchance

--- Ignoreland