my hunch is it will not make a difference, and i think B::Deparse backs me up on this..

$ perl -MO=Deparse -e '
> package main;
> use Test;
> use constant DEBUG => 0;
> my $t = Test->new();
> 
> package Test;
> use constant DEBUG => 0;
> sub new {
>     print "Test->new(@_)" if ( DEBUG || main::DEBUG() );
>     # ...
> }
> '
use Test;
use constant ('DEBUG', 0);
my $t = 'Test'->new;
package Test;
sub BEGIN {
    require constant;
    do {
        'constant'->import('DEBUG', 0)
    };
}
sub new {
    0;
}
-e syntax OK
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