I was reading this excellent post on "Diagnosing Plan Cache Related Performance Problems and Suggested Solutions” by the Microsoft SQL programmability & API development team, and was struck by the following statements:
“If the numbers of collisions (and spins) for SPL_MUTEX is high, then examine your application code to see if queries are being executed under a security context other than the sysadmin.”
“Changes to the application code that avoid this problem include executing all queries under the context of sysadmin to bypass security checks.”
Now, this particular problem has been fixed in SQL Server 2005 SP2. But these statements jogged my memory and I could swear that I had seen similar reports/articles on sysadmin having material performance advantage over non-sysadmin accounts beyond the fact that there is no permission check on the former. But I wasn't able to find any evidence to support that. So it’s possible I was just hallucinating.
Have you seen any cases where sysadmin has definite performance advantage?