I have recently upgraded my databases from SQL Server 2000 to SQL Server 2005 using attach database. Currently, all of my databases are set to compatibility level of "SQL Server 2000". Will I see any performance gains by switching these databases to "SQL Server 2005" or any performance loss by leaving them at "SQL Server 2000"? I plan on setting them to "SQL Server 2005" at some point, but was just curious to know what the performance issues are (if any).