dts decoder performance result with avconv

Following tests are based on latest libav git. built with same configurations. The result is even stranger than gst-ffmpeg with sync.

time avconv -i nfsroot2/bitstreams/720p/Source.Code.2011.BluRay.720p.DTS.x264-CHD.mkv -t 0:1:0 -f s16le a.pcm panda -- 8.345s mx53 -- 54.678s

time avconv -i nfsroot2/bitstreams/720p/Source.Code.2011.BluRay.720p.DTS.x264-CHD.mkv -t 0:1:0 -f s32le b.pcm panda -- 9.419s mx53 -- 63.294s

mru, how can I enable profile instruments in libav, any configuration options? Why native gcc in linaro releases can't support neon instructions? I think both above platforms support neon.