First thing that comes to mind is you've got a complex query with some of these UDFs involved in the middle, rather than just transforming the end result. Doing

First thing that comes to mind is you've got a complex query with some of these UDFs involved in the middle, rather than just transforming the end result. Doing the equivalent without UDFs would be an entirely different query with a different plan, or more likely you'd have to split into separate queries.