I have a VSTO app (VS 2008) that allows users to combine data from 2
or more Excel 2007 worksheets in the active workbook. Currently I am
sending the data back to SQL Server to do the heavy lifting. I'm
looping over the rows and inserting each via a stored proc.
Unfortunately with anything over a hundred or so rows it runs really
slow and I am running into MDA messages (ContextSwitchDeadlock was
detected).

Is there a better/faster way to load this data into SQL Server?

I like VSTO as opposed to VBA which I understand may be faster at this
because it provides a nice add-in that users can add or remove.

SSIS is not really an option for me because the data will in the
sheets will be generated on the fly by the user based on an OLAP
drillthrough - so I would prefer not to have to save the file.

Any thoughts are appreciated.