Note that hashing will only work out as better if you need to find several elements. IIRC the tradeoff is around 7 elements or so, above that and building the hash works, less and you might as well grep.

And if you want to create the hash, the fastest way I know of is: 

my %is_there;
undef(@is_there{@list});

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In reply to Re (tilly) 1: Quickly finding an element in an array by tilly
in thread Quickly finding an element in an array by tomhukins

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