use Benchmark 'cmpthese';

cmpthese -1, {
              'shift'=> sub { 
                            my $x=shift;
                            my $y=shift;
                            my $z=shift; 

                            return
                        },
              'assign'=> sub { 
                            my ($x,$y,$z)=@_; 
                         },
		    };
__END__
Benchmark: running assign, shift, each for at least 1 CPU seconds...
    assign:  2 wallclock secs ( 1.23 usr) @ 505470.78/s (n=622740)
     shift:  3 wallclock secs ( 1.01 usr) @ 435373.52/s (n=440598)
           Rate  shift assign
shift  435374/s     --   -14%
assign 505471/s    16%     --