This gathers the same information (ie. counts character at position in the string), and runs roughly 40 times faster.

(Faster still if you don't need the tr///). 

my %c;
$string =~ tr[ACGT][N]c;
$c{ substr $string, $_, 1 }[ $_ ]++ for 0 .. length( $string )-1;

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In reply to Re: Iterating over string by BrowserUk
in thread Iterating over string by danielfortin86

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