[Icecast] cpu usage for ices and oggenc

[Andy Baxter]

I'm running ices-kh to stream from jack at 64kbps, and also using oggenc
(with ecasound via jack) to record the audio to disk at the same time.
This is also running at 64kbps.

ices is using virtually no cpu (0.0%), but oggenc is using 15-16%. I can't
see why there should be such a difference - both are recording the same
audio stream in real time at the same bitrate. oggenc is getting its input
as a raw audio pipe from ecasound. I checked with ldd, and both are using
the same version of libvorbisenc.

Why is this happening?