Assuming that the IPC between your users query and the sub-agent uses either a filehandle or socket, then How do I print to more than one file at once? might be of some use.

You could use this trick so that if the sub-agent already has a handle open (i.e. it is currently in the process of getting the required data) it could just tack on to the handle the other users query. That way the sub-agent could satify both requests with just one lookup.

Of course I'm making assumptions about how the IPC works and so this advice could be totally useless. :)

!unlike

"The price if ignorance, which is of course that you must learn from those who know." Scorates (paraphrased)