Don't guess! Benchmark! 
use List::Util;
use Benchmark 'cmpthese';

our($h0, $h1, $h2, $h3);
our @vals = map {int rand 100} 1 .. 4;

$$h0{key0} = $vals[0];
$$h1{key1} = $vals[1];
$$h2{key2} = $vals[2];
$$h3{key3} = $vals[3];

our($m1, $m2, $m3, $m4, $m5, $m6);

cmpthese -1 => {
    h1  => '$m1 = List::Util::max values %$h0, values %$h1, 
                                  values %$h2, values %$h3',         
    h2  => '$m2 = List::Util::max map {values %$_} $h0, $h1, $h2, $h3'
+,
    h3  => '$m3 = (sort values %$h0, values %$h1,
                        values %$h2, values %$h3)[-1]',         
    h4  => '$m4 = (sort map {values %$_} $h0, $h1, $h2, $h3)[-1]',
    l1  => '$m5 = List::Util::max @vals',
    l2  => '$m6 = (sort @vals)[-1]',
};

__END__
        Rate   h4   h2   h3   h1   l2   l1
h4  160777/s   -- -37% -46% -66% -68% -89%
h2  255999/s  59%   -- -13% -46% -49% -83%
h3  295080/s  84%  15%   -- -38% -42% -80%
h1  477204/s 197%  86%  62%   --  -6% -68%
l2  506415/s 215%  98%  72%   6%   -- -66%
l1 1483834/s 823% 480% 403% 211% 193%   --

[download]
Your guess it right though. Even the fastest solution using hashes (in combination with List::Util::max) is slower than sorting the list and taking the last element.

In reply to Re^2: Getting Max Value from Different Hashes by Anonymous Monk
in thread Getting Max Value from Different Hashes by neversaint

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