How much memory do you have available? The following test case on my system uses 34 MB (according to top) after having filled the hash, and a total of 110 MB after having created the dump string.

#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my $key_ = '//programfiles/documents/data/lookup/script_auth_pap.h';
my $val_ = 'root\edit\perl\scripts\scripths\sec\inc\script_auth_pap.h'
+;
my $c = 0;
my %hash;

for (1..125000) {
    my $key = "$key_$c";
    my $val = "$val_$c"; $c++;
    
    $hash{$key} = $val;
}

<>;   #  34 MB
my $dump = Dumper \%hash;
<>;   # 110 MB
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