New in SQL Server 2008 - optimize for ad hoc workloads - Option

The optimize for ad hoc workloads option is used to improve the efficiency of the plan cache for workloads that contain many single use ad hoc batches. When this option is set to 1, the Database Engine stores a small compiled plan stub in the plan cache when a batch is compiled for the first time, instead of the full compiled plan. This helps to relieve memory pressure by not allowing the plan cache to become filled with compiled plans that are not reused.

exec sp_configure  'show advanced options', 1
reconfigure with override
go
exec sp_configure 'optimize', 1
reconfigure with override