在PHP中加速递归功能

Question

帮助我加快这个

function _NEW_COMPRESS_USER($master,$level,$str='',$YEAR_ID,$MON_ID,$Firsttime){
            global $db;
            global $_sath;
            global $_UP_LEVEL;
            if ($Firsttime){$_UP_LEVEL=$level+1;}

            if($level!=0){
            $user=$db->select('SELECT tbl_users.*,`tbl_user_active`.main_tain AS mn, `tbl_user_active`.*
        FROM tbl_users inner join `tbl_user_active`  on `tbl_users`.`id`=`tbl_user_active`.`user_id` WHERE  tbl_users.mode<>2 AND
              `tbl_user_active`.month='.$MON_ID.'  AND `tbl_user_active`.year='.$YEAR_ID.' AND  tbl_users.upuser_id ="'.$master.'" ');
            for($i=0;$i<count($user);$i++){
                if(($user[$i]['mn']==1) && ($user[$i]['mode']==1) && ($user[$i]['year']==$YEAR_ID) && ($user[$i]['month']==$MON_ID) ){
                    if(($_UP_LEVEL-$level)==1){$_sath++;}
                    $str0.=$user[$i][0].sprintf('%02s',($_UP_LEVEL-$level)).sprintf('%02s',($_sath))._NEW_COMPRESS_USER($user[$i][0],$level-1,$str0,$YEAR_ID,$MON_ID,false);
                }else{
                    $str0.=_NEW_COMPRESS_USER($user[$i][0],$level,$str0,$YEAR_ID,$MON_ID,false) ;}
                }
            return $str0;
            }

1. 这是普通文字。
2. 这是，但现在遵循代码块：