How to optimize this trigger?

[li grewat]

In a project ,I have written a trigger before insert. However, I found it is not ideal,It is too slow,How should I optimize this trigger?
The most important is that in four select ,there are the same condition "maxrid-rid<1000", can it be optimized ? The relational sql script is as follows:
-------------- BEGIN -------------------------
BEGIN
DECLARE snumc_c CURSOR FOR select count(dstaddr) from tcpflow where srcaddr=NEW.srcaddr and maxrid-rid<1000;
DECLARE EXIT HANDLER FOR NOT FOUND SET NEW.sipcdip =0;
OPEN snumc_c;
FETCH snumc_c INTO num;
set NEW.sipcdip =num;
CLOSE snumc_c;
END;

BEGIN
DECLARE dnumc_c CURSOR FOR select count(srcaddr) from tcpflow where dstaddr=NEW.dstaddr and maxrid-rid<1000;
DECLARE EXIT HANDLER FOR NOT FOUND SET NEW.dipcsip =0;
OPEN dnumc_c;
FETCH dnumc_c INTO num;
set NEW.dipcsip =num;
CLOSE dnumc_c;
END;

BEGIN
DECLARE spnumc_c CURSOR FOR select count(dstaddr) from tcpflow where srcport=NEW.srcport and maxrid-rid<1000;
DECLARE EXIT HANDLER FOR NOT FOUND SET NEW.sportcdip =0;
OPEN spnumc_c;
FETCH spnumc_c INTO num;
set NEW.sportcdip =num;
CLOSE spnumc_c;
END;

BEGIN
DECLARE dpnumc_c CURSOR FOR select count(srcaddr) from tcpflow where dstport=NEW.dstport and maxrid-rid<1000;
DECLARE EXIT HANDLER FOR NOT FOUND SET NEW.dportcsip =0;
OPEN dpnumc_c;
FETCH dpnumc_c INTO num;
set NEW.dportcsip =num;
CLOSE dpnumc_c;
END;

--------------------END -----------------------------------
Can it be query only once for the condition "maxrid-rid<1000 " and then the four sentence can use it ?
Thanks very much