use strict;
use warnings;
use Benchmark 'cmpthese';

sub linsearch {
	my ( $array, $item ) = @_;
	my $index = 0;
	$index++ while $index < @$array && $array->[$index] ne $item;
	return $index < @$array ? $index : -1;
}

sub fast_linsearch {
	my ( $array, $item ) = @_;
	my $index = -1;
	push @$array, $item;
	1 while $array->[ ++$index ] ne $item;
	pop @$array;
	return $index < @$array ? $index : -1;
}

our $array = $array =[ 1 .. 100 ];
cmpthese(
	-1,
	{
		lin_s  => 'linsearch($::array,100)',
		fast_s => 'fast_linsearch($::array,100)',
	}
);
__END__
Benchmark: running fast_s, lin_s, each for at least 1 CPU seconds...
    fast_s:  1 wallclock secs ( 1.01 usr +  0.00 sys =  1.01 CPU) @ 11182.81/s (n=11317)
     lin_s:  1 wallclock secs ( 1.03 usr +  0.00 sys =  1.03 CPU) @ 5761.40/s (n=5940)
          Rate  lin_s fast_s
lin_s   5761/s     --   -48%
fast_s 11183/s    94%     --