I had hoped that the new 1.2 version of the API would fix this issue - the release notes certainly seem to suggest that the spatial index is now being used correctly.
However I am still seeing a problem.
When I search on a large database within a small envelope, while the calls to enumRows->Next() that successfully return a found row within my envelope return quickly, the final call to enumRows->Next() which returns NULL indicating that there are no more rows with the envelope takes a very long time (i.e. upto 30 seconds in my example).
So something is still not right.
Simon