Page History

...

For example: SELECT * FROM Northwind.dbo Employees is a fully-qualified object reference whereas SELECT * FROM Employees is a poorly-qualified object. You can reuse the execution plans of fully-qualified objects "as is," whereas plans where you either cannot reuse the not fully-qualified objects or, if they are reused, then they are subject to a highly restrictive COMPILE lock while SQL Server determines if all of the objects referenced in the T-SQL code have the same owners as the execution plan currently in cache. Both of these situations consume a significant amount of CPU time.

...