BBB debian 3.8 pulseaudio echo cancellation CPU usage

[Peter Gregory]

I am running Linux beaglebone 3.8.13-bone72 #1 SMP Tue Jun 16 21:36:04 UTC 2015 armv7l GNU/Linux.
I'm building a voice controlled clock radio using PocketSphinx & mplayer & pulseaudio.
I have a USB sound adapter for playback / recording.
I loaded module-echo-cancel in pulse audio.

/etc/pulse/default.pa:

load-module module-echo-cancel source_name=echosource sink_name=echosink aec_method=webrtc
set-default-sink echosink
set-default-source echo source


/etc/pulse/daemon.conf:

resample-method = trivial
enable-remixing = yes
enable-lfe-remixing = yes
default-sample-format = s16le


I want to play a radio stream at 48khz and record with the microphone at 16khz for speech recognition.

Playing a radio stream:
mplayer -playlist http://provisioning.streamtheworld.com/pls/WRLTFMAAC.pls

Recording voice from the microphone:
parec --record --rate=16000 --channels=1 --file-format=wav test.wav

The CPU goes 100% and stays there.
The speaker output has lots of artifact sounds (pops and clicks)
The recording is not echo cancelled well.

It seems like the beaglebone is unable to process fast enough to do echo cancellation.

Has anyone gotten this to work?
Is the beaglebone underpowered for this task?