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

my @array = ("a1 b1", "a2 b2", "a3 b3", "a5 b5", "a4 b4");

sub mapBenchmark {
    my %hash = map { split( / /, $_, 2 ) } (@_);
    return \%hash;
}

print Dumper mapBenchmark(@array);