unfortunately not - we upgraded the app recently and the isolation level was necessary as part of that version change. rather strangely there are 3 instances and only 1 has the problem, despite the search running (that seems to be the cause) being fairly general.

i'm not sure if additional indexing on the table in question my help? i think it would only improve performance, since it will return as many records as it needs to return, but as long as the order-by remains, it will need to do the sort within tempdb