use Mojo::IOLoop;
my $clients = {};
my $lasttime = time;
Mojo::IOLoop->recurring(
    1 => sub {
        if ( my( $newMessages, $time ) = GetNewFromDb($lasttime) ) {
            $lasttime = $time;
            for my $msg (@$newMessages) {
                MsgToClients( $msg, $clients );
            }
        }
    },
);
websocket '/echo' => sub {
    ...
    $self->receive_message(
        sub {
            my ($self, $msg) = @_;
  
            MsgToDb( $self, $msg ); 
## NO ##    MsgToClients( $self, $msg , $clients ); ## NO
        },
    );
    ...
};
sub GetNewFromDb {
    my( $lasttime ) = @_;
    ...
    my $time = eval { $last_message->{time} };
    return $messages, $time;
}