Fix ADO.NET slow query performance while the same query runs fast in SSMS

• 1 Check ARITHABORT ON/OFF setting on SQL Server:
  /* TEST FOR ARITHABORT ON */
  DECLARE @options TABLE ([name] nvarchar(35), [minimum] int, [maximum] int, [config_value] int, [run_value] int);
  INSERT INTO @options ([name], [minimum], [maximum], [config_value], [run_value])
  EXEC sp_configure 'user_options';
  SELECT [setting] = 'ARITHABORT ' + CASE WHEN ([config_value] & 64) = 64 THEN 'ON' ELSE 'OFF' END
  FROM @options;
  GO
  
• 2 Set ARITHABORT ON globally on single database when it is turned OFF:
  
• 3 USE [master]
  GO
  IF (EXISTS (SELECT * FROM sys.databases db WHERE db.[name] = N'{DbName}' AND db.[is_arithabort_on] = 0))
  BEGIN
  --ALTER DATABASE [{DbName}] SET ARITHABORT ON WITH NO_WAIT;
  END
  
• N Beware that changing this setting may break some existing applications. Read the documentation first: https://docs.microsoft.com/en-us/sql/t-sql/statements/set-arithabort-transact-sql?redirectedfrom=MSDN&view=sql-server-ver15
  

References

• https://www.mssqltips.com/sqlservertip/4318/sql-server-stored-procedure-runs-fast-in-ssms-and-slow-in-application/
• https://blog.sqlauthority.com/2018/08/07/sql-server-setting-arithabort-on-for-all-connecting-net-applications/
• https://dba.stackexchange.com/questions/2500/make-sqlclient-default-to-arithabort-on