#! perl -slw
use strict;
use Benchmark qw[ cmpthese ];

sub f1 { # ( [$:arg] )
    use 5.007003; # perl v5.7.3; required for List::Util to be available in CORE
    use List::Util qw/ first /;
    my $arg = first { defined && length } ( shift, 'default_value' );
    $arg;
}

sub f2 {
    my $arg = defined $_[0] && length $_[0] ? shift : 'default';
    $arg;
}

our $ITERS //= 1000;
our @args = ( undef, '', 'fred', 1, 1.5 ) x $ITERS;

cmpthese -1, {
    stupid => q[ f1( $_ ) for @args ],
    simple => q[ f2( $_ ) for @args ],
}

__END__
C:\test>junk0 -ITERS=10000
         Rate stupid simple
stupid 12.8/s     --   -58%
simple 30.2/s   136%     --