Need help for cursor optimization

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Oracle

cursor

stored-procedure

Hello
I am using following procedure to update MASTER table from TEMP table
it takes 5 to 6 hrs to execute.
Can you please help me to optimise time.

TABLES USED :
TEMP : select in CURSOR (COUNT: 1.5 CR)
MASTER : to update from TEMP table using FOR LOOP (COUNT : 3 CR)
ERROR_LOG : LOG error occured in UPDATE
Field Datatype details :ID1 : Number
ID2 : Varchar2
ID3 : Varchar2

Create or Replace procedure PROC_UPDATION (updbatch number) is --updbatch to record batch size
l_rows_affacted NUMBER := 0;
l_Total_rows_affacted NUMBER := 0;
l_Totrec NUMBER:=0;
str varchar2(255);
CURSOR temp_cur IS
SELECT ID1,ID2,ID3 from TEMP; --TABLE 1 has 1 cr rows.
BEGIN 
FOR temp_rec in temp_cur LOOP
DECLARE  --internal block start to continue Loop even if Exception occures.
updexception Exception;
BEGIN  
if temp_rec.ID1 is NULL then 
    raise  updexception;
   end if;
   str:='update master set ID1 ='|| temp_rec.ID1 ||' where ID2 ='''|| ID2 ||''' and ID3='''|| ID3 ||'''';
   execute immediate str;
  --l_rows_affacted returns 1 id 
   --update successful and 0 if record not updated
  l_rows_affacted := SQL%ROWCOUNT;   EXCEPTION
   WHEN updexception then
   l_Total_rows_affacted:=l_Total_rows_affacted -1;
   insert into error_log values(sysdate,'UPDATE FAILED',LOG_SEQ.NEXTVAL);
   commit;
  END;  
END LOOP; --Loop End
EXCEPTION
 when others then
 insert into error_log values(sysdate,str,LOG_SEQ.NEXTVAL);?commit;
END;
/

[edit]SHOUTING removed, Code block added - OriginalGriff[/edit]