Memory leak of iterations in large hash.

Hi, I compared one element with others in a Hash (size : about 7,000).

------------------------------------------------------------------------
for(word1 in arrword)
{
   for(word2 in arrword)
   {
       # compare word1 with word2.
   }
}
------------------------------------------------------------------------

But, in every iteration, the memory-usage increased.

Somebody help me?

Thanks.
Remi.