use Benchmark qw(cmpthese); my $a1='a'x1e6; my $b1=12345; cmpthese -1,{ a=>q[ sub{ my( undef, $x) = @_ }->( $a1, $b1 ) ], b=>q[ sub{ my $x = $_[1] }->( $a1, $b1 ) ], c=>q[ sub{ my( $unused, $x ) = @_;}->( $a1, $b1 ) ], }; # Output Rate c a b c 649176/s -- -3% -33% a 670690/s 3% -- -30% b 963764/s 48% 44% --