Dynamics AX ERP (version 2009) Performance is very slow

Our Microsoft Dynamics AX ERP (version 2009) is very slow.

• One of the HDD (Raid 0) of the production server broken, the MS-SQL Transaction log file stored in this HDD.
• We backup the DB from the production server to a temp server.
• We restore the DB to the temp server.
• We rebuild the transaction log file from the restored DB in the temp server.  We use this command:
  • ALTER DATABASE DynamicsAX_PRO SET SINGLE_USER WITHROLLBACK IMMEDIATE
  • DBCC CHECKDB('DynamicsAX_PRO',REPAIR_ALLOW_DATA_LOSS
• We turn on the temp server for users to use
• We replace the HDD and set it to Raid 1
• We back up the DB from the temp server
• We restore the DB to production server
• We found the performance is slow, then we switch Raid 1 back to Raid 0
• Performance is slow, therefore we re-installed MS-SQL Server 2008 R2 again
• Performance is slow
• We performed maintenance functions
  •   Integrity (1^st time failed, 2^nd time took @ 2 hours)
  •   Re-organize (@ 7 hours and 39 minutes)
  • Update Stats (@ 7 hours and 27 minutes)
• Performance is still slow
• We then perform rebuild index (@ 3 hours)
• Performance is still slow