http://www.perlmonks.org?node_id=1064827


in reply to Faster Hash Slices

What Eily says. Then, according to perldata:

You can preallocate space for a hash by assigning to the keys() function. This rounds up the allocated buckets to the next power of two: 
           keys(%users) = 1000;                # allocate 1024 buckets

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I'm not sure about the impact on performance, though.

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

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