sub s1{ $_[0] + $_[1] }
sub s2{ my( $x, $y ) = @_; $x + $y; }

cmpthese -1, { 
    a=>q[ my $z = s1( 1, 2 ); ], 
    b=>q[ my $z; { my( $x, $y ) = (1,2); $z = $x + $y } ], 
    c=>q[ my $z = s2( 1, 2); ], 
    d=>q[ my $z = 1 + 2; ], 
};;
        Rate    c    b    a    d
c  1452758/s   -- -38% -42% -88%
b  2344698/s  61%   --  -6% -81%
a  2483364/s  71%   6%   -- -80%
d 12297390/s 746% 424% 395%   --