Compare 2 very large arrays of long strings as elements

onlyIDleft has asked for the wisdom of the Perl Monks concerning the following question:

Dear Monks,

I have 2 very large arrays (~ 2 million ) that I need to extract the unique elements out of.The array elements themselves are long strings up to 60 or 70 characters each

What is the fastest way of performing this extraction? I tried to use the code from http://www.perlmonks.org/?node_id=335021, but my script is still running :( for > 8 hours!!!

use Quantum::Superpositions;
@a2 = eigenstates(any(@a2) != all(@a1));
[download]

Please bless me with a faster way to extract uniques from each array list. Thank you all

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