In an earlier post, I highlighted that linked server security configuration can have a huge performance impact, and complained that this was not properly documented in SQL Server Books Online and filed a Connectitem for this. Good news is that in Books Online for SQL Server 2008 R2,  Microsoft has revised the documentation, and included the ...

If you change the security configuration of a linked server from using login UserA to login UserB, would you expect that to significantly impact the performance of a query that uses the linked server, assuming that both users have permission to select from the remote table referenced in the query?   Many people probably would answer no. ...