$a='a'x1e6; $b=12345; cmpthese -1,{ a=>q[ sub{ my( undef, $x ) = @_ }->( $a, $b ) ], b=>q[ sub{ my $x = $_[1] }->( $a, $b ) ], c=>q[ sub{ my( $unused, $x ); }->( $a, $b ) ], };; Rate a b c a 1703708/s -- -19% -20% b 2107186/s 24% -- -1% c 2129207/s 25% 1% --