Your comment #not creating with .. operator, mem efficient is somewhat outdated, as for several major releases now (at least since 5.005_03) the .. operator has not created a masive temporary array as it was wont to do in earlier times. So unless you are using an old version of Perl, please feel free to use  for(1..1_000_000) without fear, and avoid clumsy alternatives!

Update: Back to your topic, this little exercise isn't a new idea, but it is a good thing to try in order to get some understanding of rand. You might try different pseudo-random number generation functions (a quick google should turn up lots) or indeed some CPAN options) and compare the results, especially if you are going to rely on rand for any meaningful purpose (e.g. we use Monte-Carlo economic simulations on occasion). You might also consider the distribution being generated - the built-in functions typically generate uniform distributions, but for many purposes that isn't immediately suitable. In the real world however, if you do need lots of pseudo-random numbers you're most likely better off with a non-default algorithm coded in C for speed, or some real randomness.