[iiwusynth-devel] Major improvement

[Peter Hanappe]

I started profiling the iiwusynth (using rdtsc based timing) and
figgered out that most of the time the synthesizer was generating sounds
we don't hear at all (subliminal messages ;). 

Most of the presets have a rather long release, say ~800 msec. If a note
only takes 200 msec, the synth spent 80% of the time in the release
phase of the note. So instead of waiting for the nore to reach the end
of the release phase I cut it off when the amplitude envelope reaches
-100 dB (not really a genious idea but still you have to find the
troublemaker).

Net result: a 50% cut in CPU usage!

Some of my MIDI files dropped from 45% CPU usage to less than 20%. If I
play them without reverb, it goes even down to 10%!

I've also added some options to turn the reverb on/off and set the
master gain on the command line. All committed to CVS.

Cheers!
Peter