asterisk users - Jun 2006 - Monitoring transcoding and other heavy activities

Hi,
often on this list I read about transcoding as the heaviest activity for an
Asterisk server, together with high IRQ rate (especially with Digium
cards...).
Is there a way to monitor if Asterisk is engaged (by mistake or by design)
in transcoding or any other heavy activity?
Or a checklist to follow to diagnose these 'bad' behaviours?

Thanks
DV