To be totally honest once I found those couple of insert statements being slow in the stored procedure I concentrated on why they are causing slowness. Perhaps if I watched profiler for a bit longer I would see other data mod t-sql in that proc being slow too.

We are using a vendor app.

You comment about using a table-valued parameter sounds good. But are table-valued parameter persistent across procedure calls - I thought no. If they aren't how would that work?