GL Account Group - Slow adding new items

I'm so happy that the GL Account Group can add with multiple levels - subgroup of. However, when I add more and more items into it generating multi-levels, the data entry becomes slower and slower but when I view on the database table, the data is merely less than 10Kb.

Any idea why it is like that?

I also found a php script that says can repair the mysql table - repair.php

<?php
require("config.php");
$host = $dbhost;
$database = $dbname;
$username = $dbuname;
$password = $dbpass;
mysql_connect($host, $username, $password);
@mysql_select_db($database);
$res = mysql_query("repair table ".$prefix."_XXXX");
if ($res) {
    echo $res;
} else {
    print (mysql_error());
}
?>

The outcome result I got was "Resource id #4"

Any idea on what it means? Just want to know how I can overcome the slow processing of data entry.

Thanx a million