Hello batrams,

On each iteration you push the contents of the next array onto @newArr, but this array is never cleared, so by the end of the while loop you are greping through every element in every array within %HoA! It’s not surprising that this is very slow!

But I don’t understand why you need to construct the array at all. The following should be all you need:

#! perl
use strict;
use warnings;

my %HoA =
(
    no1  => [ 'c', 'd'      ],
    yes1 => [ 'X'           ],
    no2  => [ 'e', 'e', 'f' ],
    yes2 => [ 'a', 'X', 'b' ],
);

my $a = 'X';

for my $key (keys %HoA)
{
    print "Element '$a' found, key = $key\n" if grep {$_ eq $a} @{ $Ho
+A{$key} };
}
[download]

Output:

13:00 >perl 1095_SoPW.pl
Element 'X' found, key = yes2
Element 'X' found, key = yes1

13:12 >
[download]

If this is still too slow, you can replace the call to grep with something more idiomatic: see How can I tell whether a certain element is contained in a list or array?, especially the first function in the core module List::Util.

Hope that helps,