These are few tips to increase SQL Performance:

  • An index increases time to perform INSERT / UPDATE / DELETE operations.  So minimal uses of indexes should be preferred. Not more than 4-5 indexes per table
  • Indexes should be on Integer values than Character values.
  • While generating Composite Key, ensure that the most important key is on the left.
  • Clustered indexes are more preferable than nonclustered
  • If the same query is executed over and again, prefer having an index on the search criteria columns. It will enhance your performance
  • Join tables based on Integer columns than String based columns.
  • Use a SQL Server Profiler before deploying your application

I hope this helps!