Thank you. This explains everything I was attempting to, but does it lucidly. Moreover, it goes in to a lot of things I didn't know about.
Only one thing I have to add: You can find the number of items in a hash with scalar keys %hash, and the number of used/total buckets with ($used_buckets, $total_buckets) = split '/', scalar %hash. With those numbers in hand, you should be able to get more exact timings, or demonstrate to yourself that what pg says is true.
Warning: Unless otherwise stated, code is untested. Do not use without understanding. Code is posted in the hopes it is useful, but without warranty. All copyrights are relinquished into the public domain unless otherwise stated. I am not an angel. I am capable of error, and err on a fairly regular basis. If I made a mistake, please let me know (such as by replying to this node).