sub yourWay{ 
    my %h = %{ $_[0] }; 
    return %h; 
};;

sub myWay{ 
    my $ref = shift; 
    return $ref 
};;

%hash = ( 1 .. 1e6 );;

cmpthese -5,{
    a=>q[ 
        my %h = yourWay( \%hash ); 
    ], 
    b=>q[ 
        my $h = myWay( \%hash ); 
    ] 
};;
     s/iter          a          b
a      1.12         --      -100%
b 1.03e-006 108368213%         --