php response is taking too long time - php

Question

I have some problem with getting results from VFP database results... The time which is taking by my php script is veeeery long - about 30 minutes, but it should be much shorter...
So there is the code which is responsible for taking database results:
$connect = odbc_connect("RIS", "", "", SQL_CUR_USE_DRIVER) or die("Error in connection ". odbc_errormsg($connect));
$array = array();
$info = array();
$from = $_GET['from'];
$to = $_GET['to'];
$rez_nap = odbc_exec($connect, "
select
pacientid as pac_pk,
datanapr,
ocered,
rtgapparat,
doctor as doc_naprav,
pk_na,
data_opis,
arst_opis as id_arst_opis
from
napravlenie
where
not arst_opis == '0000' and
not arst_opis == '' and
datanapr between {^".$from."} and {^".$to."}
") or die(odbc_errormsg());
while($row_nap = odbc_fetch_array($rez_nap))
{
echo "<pre>";
var_dump($row_nap);
$rez_opis = odbc_exec($connect, "
select
opis as opisanie,
doctor as doc_opis
from
opisanie_rtg
where
pacientid = '".$row_nap["pac_pk"]."' and
data = '".$row_nap["data_opis"]."' and
ocered = '".$row_nap["ocered"]."'
") or die(odbc_errormsg());
while($row_desc = odbc_fetch_array($rez_opis))
{
$op = explode('##$', $row_desc['opis']);
$opisanie = iconv( "cp1257", "utf-8", trim( addslashes($op[1]) ) );
$t_nr_i = substr($op[0], 12);
$ttt = explode("[", $t_nr_i);
if ( strlen($ttt[0]) > 12 )
{
$tt_nr_is = explode("-", $ttt[0]);
$t_nr_is_t = substr($tt_nr_is[0], 0, 8);
$t_nr_is_t_2 = substr($tt_nr_is[0], 8, 5);
$row_desc["nr_is"] = $t_nr_is_t."-".$t_nr_is_t_2;
}
else
{
$t_nr_is_t = substr($ttt[0], 0, 8);
$t_nr_is_t_2 = substr($ttt[0], 8, 5);
$row_desc["nr_is"] = $t_nr_is_t."-".$t_nr_is_t_2;
}
$row_desc['opis'] = $opisanie;
/////////////////////////////////////////////////////////////////////////////////////////////////////
$rez_apparat = odbc_exec($connect, "
select
kod,
gruppa,
imy,
prefiks
from
apparatura
where
kod = '".$row_nap["rtgapparat"]."'
") or die("Error in apparatura.dbf - ". odbc_errormsg($connect));
while($row_apparat = odbc_fetch_array($rez_apparat))
{
$rez_app_gruppa = odbc_exec($connect, "
select
gruppa,
prefiks,
apparati
from
apparat_gruppa
where
gruppa = '".$row_apparat["gruppa"]."'
") or die(error_logs("Error in apparat_gruppa.dbf - ".odbc_errormsg($connect)));
while($row_app_gruppa = odbc_fetch_array($rez_app_gruppa))
{
$rez_personal = odbc_exec($connect, "
select
s_name as doc_opis_name,
f_name as doc_opis_surname
from
personal
where
number = '".$row_nap["id_doc_opis"]."'
") or die(error_logs("Error in personal.dbf - ".odbc_errormsg($connect)));
while($row_personal = odbc_fetch_array($rez_personal))
{
$row_personal["doc_opis_name"] = iconv("cp1257", "utf-8", trim($row_personal["doc_opis_name"]));
$row_personal["doc_opis_surname"] = iconv("cp1257", "utf-8", trim($row_personal["doc_opis_surname"]));
$row_personal["filial"] = "r15";
$info[] = array_merge($row_nap, $row_desc, $row_apparat, $row_app_gruppa, $row_personal);
}
}
}
}
}
echo json_encode($info);
odbc_close($connect);
the database has about ~80-90k rows with data, and I'm using odbc driver to connect to VFP database, also the database is on the remote server... Any advices what I'm doing wrong? Because I can't figure what I'm doing wrong... Thanks for any advice and help!
P.S Also I need to convert that response into JSON and then save it to MySQL database...
EDIT 1
I have the second indexes:
pacientid, data_opis, ocered into the pacient table, opisanie and napravlenie