listen 0.6.3 & 0.6.4 - MP3 playback is choppy

I just installed listen 0.6.3 on Gentoo, and tried to playback an MP3.

This does not work. The timer (which tells me how long the song has been playing) runs at ~1/3rd of it's normal speed. So it takes about 3 seconds walltime to make listen play 1 second of audio.

Obviously, the songs are hardly recognisable that way.

The CPU load goes up to about 52% per core (2 cores) during this playback.

In the terminal, the following output appears:
/usr/lib64/listen/widget/preference.py:24: DeprecationWarning: the md5 module is deprecated; use hashlib instead
  import md5
No avahi support
location: /usr/lib64/xulrunner-1.9.1/libxpcom.so
before 3
Tray icon attached
WARNING listen.player.fadebin.StreamBin stream "file:///mnt/dow...mply Red - Fairground.mp3" already blocked
ERROR listen.lastfm_information.LastFmBox 0x37ef370 Failed to load image http://www.7digital.com/shops/assets/sleeveart/150244_100.JPEG (not found)
Traceback (most recent call last):
  File "/usr/lib/listen/source/lastfm_information.py", line 272, in make_btn_lastfm
    try: sock = urlopen(image_url)
  File "/usr/lib64/listen/vfs/vfsutils.py", line 55, in urlopen
    return opener.open(req)
  File "/usr/lib64/python2.6/urllib2.py", line 389, in open
    response = meth(req, response)
  File "/usr/lib64/python2.6/urllib2.py", line 502, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/lib64/python2.6/urllib2.py", line 421, in error
    result = self._call_chain(*args)
  File "/usr/lib64/python2.6/urllib2.py", line 361, in _call_chain
    result = func(*args)
  File "/usr/lib64/python2.6/urllib2.py", line 597, in http_error_302
    return self.parent.open(new)
  File "/usr/lib64/python2.6/urllib2.py", line 389, in open
    response = meth(req, response)
  File "/usr/lib64/python2.6/urllib2.py", line 502, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/lib64/python2.6/urllib2.py", line 427, in error
    return self._call_chain(*args)
  File "/usr/lib64/python2.6/urllib2.py", line 361, in _call_chain
    result = func(*args)
  File "/usr/lib64/python2.6/urllib2.py", line 510, in http_error_default
    raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)
HTTPError: HTTP Error 403: Forbidden
ERROR listen.lastfm_information.LastFmBox 0x37ef370 Failed to load image http://www.7digital.com/shops/assets/sleeveart/207669_100.JPEG (not found)
Traceback (most recent call last):
  File "/usr/lib/listen/source/lastfm_information.py", line 272, in make_btn_lastfm
    try: sock = urlopen(image_url)
  File "/usr/lib64/listen/vfs/vfsutils.py", line 55, in urlopen
    return opener.open(req)
  File "/usr/lib64/python2.6/urllib2.py", line 389, in open
    response = meth(req, response)
  File "/usr/lib64/python2.6/urllib2.py", line 502, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/lib64/python2.6/urllib2.py", line 421, in error
    result = self._call_chain(*args)
  File "/usr/lib64/python2.6/urllib2.py", line 361, in _call_chain
    result = func(*args)
  File "/usr/lib64/python2.6/urllib2.py", line 597, in http_error_302
    return self.parent.open(new)
  File "/usr/lib64/python2.6/urllib2.py", line 389, in open
    response = meth(req, response)
  File "/usr/lib64/python2.6/urllib2.py", line 502, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/lib64/python2.6/urllib2.py", line 427, in error
    return self._call_chain(*args)
  File "/usr/lib64/python2.6/urllib2.py", line 361, in _call_chain
    result = func(*args)
  File "/usr/lib64/python2.6/urllib2.py", line 510, in http_error_default
    raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)
HTTPError: HTTP Error 403: Forbidden
WARNING listen.player.fadebin.StreamBin bin0 stream is already unlinked. huh? "file:///mnt/dow...mply Red - Fairground.mp3"
WARNING listen.player.fadebin.StreamBin bin0 stream is already unlinked. huh? "file:///mnt/dow...mply Red - Fairground.mp3"
WARNING listen.player.fadebin.StreamBin bin0 stream is already unlinked. huh? "file:///mnt/dow...mply Red - Fairground.mp3"
Exiting...
Saving column config for filesystem
Saving column config for local
Saving column config for lastfmradio
Saving column config for podcast_local
Exit successful
Listen existed

I also used strace to see what the application was actually doing. It collected 2.5MB of info in about 5 seconds. A part of the strace output can be found at:
http://pastebin.com/m47159873

- As far as I can tell, this seems to be some HAL related issue. The options for "Check for changes in media library" and "scan changes" were OFF.
- The files are on on (ntfs3g) mounted harddisk partition, but if I move them to my root filesystem (ext4), I have the same problem
- I also recompiled listen without HAL support, but still I didn't get any (usefull) playback.
- The MP3 files play fine in any other application (tested; VLC, mplayer and totem).
- With 0.6.4, I got the same problem (is not yet in portage).
- Using python 2.6.2
- The listen --debug 9 output is attached.