How Does Adding Constraints Affect Performance?

I'm considering adding domain integrity checks to some of my database table
items. How does adding such constraints affect SQL Server performance? For
example, I have a simple constraint that restricts a couple of columns to
having values within the values assigned in my application by an
enumeration:

(([Condition] >= 0 and [Condition] <=3) and ([Type] >= 0 and [Type] <=
2))

This enforces domain integrity for two enumerations having values 0, 1, 2, 3
and 0, 1, 2 in the application. Is this an efficient way of performing such
checks? What are the pitfalls of domain integrity checking?


Thanks




Robin