Still slower than bind:

{   my $t0 = [ gettimeofday ];
    my $n  = 0;
    my $rows = $dbh->selectall_arrayref ($sql, { Slice => {} });
    foreach my $row (@$rows) {
        $n++;
        }
    printf STDERR "slice: %9.2f recs/sec\n", $n / tv_interval ($t0);
    }

{   my $t0 = [ gettimeofday ];
    my ($n, %rec) = (0);
    my $sth = $dbh->prepare ($sql);
       $sth->execute;
       $sth->bind_columns (\@rec{@{$sth->{NAME_lc}}});
    while ($sth->fetch) {
        $n++;
        }
    printf STDERR "bind:  %9.2f recs/sec\n", $n / tv_interval ($t0);
    }

=>

with postgres on other server:
slice:  23842.81 recs/sec
bind:   27994.01 recs/sec

with postgres on local server:
slice: 214963.65 recs/sec
bind:  505370.38 recs/sec
[download]

YMMV