I've noticed a strange behaviour of SQL Server 2008 r2 express:

usually my query execution time is ~650ms, but if I open Management Studio and run any simple query (for example SELECT * FROM Something), the execution time becomes ~40ms. If I close management studio this value returns to normal ~650ms

And no matter where the query was executed: from Management Studio or my application (it uses ADO.Net)

ARITHABORT setting has no effect

Why is this happening?

1 Answer 1


The database you are querying probably has "auto close" enabled.

The connection from SSMS stops the database closing. When you close SSMS, the database closes. A subsequent call requires it to be opened.

Auto close is the default for SQL Server Express and is not a good idea:


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