When you try to shut down or Restart the Exchange Server 2003, it takes age to shutdown due to some of the important processes get killed during shutdown and which makes other process to get hung making the shutdown slower.
Use the below code of the batch file and put that file in the Shutdonw Script.
net stop MSExchangeES /y
net stop MSExchangeIS /y
net stop MSExchangeMTA /y
net stop MSExchangeSA /y
net stop WinHttpAutoProxySvc /y