Whenever I brought proper gprof performance profiling into the debugger code,
I immediately discovered that the biggest consumer of idle CPU usage
was my modular effects unit, which makes sense because there's:

8*(active_midi_tracks+all_audio_tracks+all_busses) +
4*(way_v_instances+euphoria_instances)

of these effects running at all times.

I implemented an indexing algorithm similar to Euphoria into Modulex,
which tracks effect type changes at a rate of once every 50 sample blocks.
This has made a dramatic difference in idle CPU usage(roughly 0% CPU
on my AMD FX8350 with a full project loaded), and unlike most competing
DAWs in Linux/Windows/OSX, I didn't have to resort to some goofy
'sleep state' for the tracks, they're all running and ready to do work,
but not consuming any detectable amount of CPU time to do it.