my $self = shift;
my %param = @_;

##</code><code>##

my ($self,%param) = @_;

##</code><code>##

use Benchmark qw(cmpthese);
cmpthese( -2,{
 list => sub { my ($self,%param) = @_ },
 shiftit => sub { my $self = shift; my %param = @_ },
} );
__END__
5.8.3       Rate    list shiftit
list     78392/s      --    -73%
shiftit 292680/s    273%      --
5.6.2       Rate    list shiftit
list     94936/s      --    -68%
shiftit 297717/s    214%      --

##</code><code>##

sub list { my ($self,%param) = @_ }
sub shiftit { my $self = shift; my %param = @_ }

cmpthese( -2,{
 list => sub { list( qw(foo bar baz) ) },
 shiftit => sub { shiftit( qw(foo bar baz) ) },
} );
__END__
5.8.3      Rate shiftit    list
shiftit 70621/s      --    -11%
list    79125/s     12%      --
5.6.2      Rate shiftit    list
shiftit 89341/s      --    -10%
list    98866/s     11%      --

##</code><code>##

cmpthese( -2,{
 list => sub { list( qw(foo) ) },
 shiftit => sub { shiftit( qw(foo) ) },
} );
__END__
5.8.3       Rate shiftit    list
shiftit 164545/s      --    -19%
list    204158/s     24%      --
5.6.2       Rate shiftit    list
shiftit 179408/s      --    -12%
list    203990/s     14%      --

##</code><code>##

cmpthese( -2,{
 list => sub { list() },
 shiftit => sub { shiftit() },
} );
__END__
5.8.3       Rate shiftit    list
shiftit 217350/s      --    -12%
list    247334/s     14%      --
5.6.2       Rate shiftit    list
shiftit 212031/s      --    -14%
list    246447/s     16%      --

##</code><code>##

To call subroutines:

           NAME(LIST);    # & is optional with parentheses.
           NAME LIST;     # Parentheses optional if predeclared/imported.
           &NAME(LIST);   # Circumvent prototypes.
           &NAME;         # Makes current @_ visible to called subroutine.

##</code><code>##

cmpthese( -2,{
 list => sub { &list },
 shiftit => sub { &shiftit },
} );
__END__
5.8.3       Rate    list shiftit
list    126315/s      --    -62%
shiftit 333577/s    164%      --
5.6.2       Rate    list shiftit
list    135814/s      --    -61%
shiftit 343986/s    153%      --