Advanced Queue Latency

Oracle 10.1.0 on LINUX
Using DBMS_AQ.

I am trying to send messages from instance ORCLA to instance ORCLB
on another machine.
I am experiencing a delay of about 20 seconds between the enqueue time
and the dequeue time.
Latency is set to zero in the enqueue.
I have a daemon listening for messages.
I have tried changeing the hidden _job_queue_interval from 5 seconds to
1 second with no effect.

I read someplace that AQ batches messages.
Is this true? Can batching be controlled?

What else can I do to reduce latency?

Thanks

Dave R