wow. I have been an informal dba (i.e. the only person willing to look into it) since SQL 6.5 but I cannot answer any of those questions. I am sure...

I updated stats on person and reqTablePref, recompiled the sp and function.

On the execution plans, they start with a clustered index scan on reqTablePref which is 78% (77% on...

Didn't know functions were slow, thanks for the info!

As for differences in rows between test and production: The Person tables both have the same (128000), and the reqTablePref tables are...

No joy

Still takes 16-18 seconds to execute.

3 of us have looked at this db just to make sure we haven't missed anything....