게시물이 많을 경우 해당될거 같은데요..
wr_num을 추출해서 인덱스를 타게 한겁니다.
설명이 맞나 모르겠네요.


comment_view.php에서

$sql = " select * from $write_table where wr_parent = '$wr_id' and wr_is_comment = 1 order by wr_comment, wr_comment_reply ";

를

$n = mysql_result(mysql_query("select wr_num from $write_table where wr_id='$wr_id'"), 0, 0);
$sql = " select * from $write_table where wr_num = '$n' and wr_is_comment = 1 order by wr_comment, wr_comment_reply ";

로 수정