Oracle proc call from CF has 4sec overhead

G'day
I've been troubleshooting a slow-running Oracle (9i) proecdure call, which
was coming in at 4sec. When run via a Oracle SQL Developer window, it runs
in 0ms, which is more like what I'd expect form the amount of work it's
doing.

I applied FusionReactor to the situation, and it's reporting that the proc
is indeed *running* in 0ms, but the added overhead of CF calling it is
4sec. From the "Longest JDBC" screen, the figures were:

Total Time(ms): 3845
DB Time(ms): 0

What on earth is CF doing?

Notes:
- it's returning zero rows, so it's not a data-transmission overhead.
- the DB is running on the same box as CF.
- it's not a one-off. Running the proc with different input data (which
would yield any number of rows returned from 0 to 30000-odd) seems to make
little difference. The DB side of things runs between 0-100ms, and then
there's close to a 4sec overhead added by CF.

The stored proc is running a couple of select queries (a value from the
first contributing to the second), and returning a single resultant record
set. Nothing complicated.

Any ideas?

--
Adam