Cursor taking much longer time

Question

Is there any solution to optimize this? As it is taking more than 2 hours to update the table.
Stats about the table records count:
table_1 = 0.3milliions
table_2 = 89k
table_3 = 2.5 millions
table_4 = 6k
=========================================
cursor c1 is
SELECT SUM (A.w_amount) AS total_comp, D.emp_no
FROM table_1 A,
table_2 B,
table_3 C,
table_4 D
WHERE A.emp_no = B.emp_no
AND A.check_id = B.check_id
AND A.emp_no = C.emp_no
AND D.emp_no = C.emp_no
AND A.earn_code IN ('REM')
AND B.check_date >= C.elig_dt
AND ee.time_s_key = user2.time_pkg.fx_time_key()
GROUP BY D.emp_no;
BEGIN
FOR cur_row IN c1
LOOP
UPDATE table_4
SET gross_comp = cur_row.total_comp
WHERE cur_row.emp_no = table_4.emp_no;
END LOOP;
END;
======================================

Answer 1

time_key_var := user2.time_pkg.fx_time_key();
update table_4 D
set gross_comp = (
SELECT SUM (A.w_amount) AS total_comp, D.emp_no
FROM table_1 A,
table_2 B,
table_3 C
WHERE A.emp_no = B.emp_no
AND A.check_id = B.check_id
AND A.emp_no = C.emp_no
AND D.emp_no = C.emp_no
AND A.earn_code IN ('REM')
AND B.check_date >= C.elig_dt
AND ee.time_s_key = time_key_var
GROUP BY D.emp_no
where exists (
SELECT null
FROM table_1 A,
table_2 B,
table_3 C
WHERE A.emp_no = B.emp_no
AND A.check_id = B.check_id
AND A.emp_no = C.emp_no
AND D.emp_no = C.emp_no
AND A.earn_code IN ('REM')
AND B.check_date >= C.elig_dt
AND ee.time_s_key = time_key_var
);