The original code updates every record for the person, irrespective of whether it changes or not. I think updating only the rows that change makes up for any inefficiency with an "IF" statement.

I put the two procedures in the database and looked at the execution plans. It is not always an accurate reflection of execution time, I know, but it does provide very useful information. The original procedure was expected to take 66% of the time and the revised procedure was expected to take 34%. The compiler seems to think the "IF" statements are not a significant detriment.

I have one other thing to note. The original procedure accepts as parameters both the PersonID and the ToDoID. The PersonID is dependent on the ToDoID, so either the procedure should not accept the PersonID as a parameter and just look it up, or it should validate that the PersonID passed was the correct PersonID for the ToDoID.