Try to change codec priority to h264,vp8
codecs=opus,alaw,ulaw,g729,speex16,g722,mpeg4-generic,telephone-event,h264,vp8,flv,mpv
then update to latest available version
service webcallserver update
You have such load on WebRTC tests because WCS transcodes H.264 to VP8 in Full HD resolution.
Such...