Microsoft® SQL Server 2012 Unleashed

T-SQL or CLR Stored Procedures?

One question that often comes up is whether it’s better to develop stored procedures in T-SQL or in the CLR. The best answer is that the method you choose really depends on the situation and what functionality the procedure needs to implement.

The general rule is that if the stored procedure will be performing data access or large set-oriented operations with little or no complex procedural logic, it’s better to create the procedure in T-SQL for best performance. The reason is that T-SQL works more closely with the data and doesn’t require multiple transitions between the CLR and the SQL OS.

However, most benchmarks have shown that the CLR performs better than T-SQL for procedures that require a high level of computation ...