Subject Insert into Large Table is slowly!
Hello, every body!
  I have a 180GB database. and have a large table in it. 
table's DDL is:
Create Table Table1
   f_MeterID Integer,
   f_CMDID smallInt,
   f_Time timestamp,
   f_Value Numric(12,2),
   f_RecTime Timestamp
Create Index idx_Table1 on(f_MeterID, f_CMDID, f_Time)

about 50,000 rows be inserted every hour. 
about 1.2 millions rows be inserted every day. 
about 500 millions rows every year.

I insert data use follow:
1. start a transaction
2. Insert a batch records into temp table TableTemp, It's structure like table1
3. Insert into Table1 select * from TableTemp
    Delete Data From TableTemp
    (about 30,000 record every tiime)
4. commit transaction

but now, insert data become very slowly.

What should I do?