Thanks for the feedback. Are there any others experiencing this same issue with other devices?
One workaround would be to setup a Syslog rule specific to each Netscreen devices so that it only triggers RTCD download action for the first event and suppresses further actions for X seconds before triggering again.
That workaround would address the performance issue, but will typically miss the rest of the changes until either a later change set or the nightly download (rather defeating the purpose of RTN). I could probably set the event to fire the autodownload event, script up a delayed autodownload event, and suppress for the duration of that delay. This becomes a pretty ugly hack, through.