Sending packets after RELAY_END
If you run Camilo Viecco's test program at:
svn checkout http://tdor.googlecode.com/svn/trunk/testing/
you'll notice that once the program cuts off the downloads at 30 seconds or so, Tor continues to report hefty incoming bandwidth.
The attached dump from Wireshark shows that long after the client has sent a RELAY_END cell for stream 11629 it continues to receive data for that stream from the exit. A rough calculation suggests about 30K worth of data is received after the RELAY_END.
I think this is the exit flushing it's cell queue, but given the client officially stopped caring after RELAY_END that's quite a bit of wasted bandwidth.
(To read the attached dump search for 'RELAY_END' and keep searching until you find the RELAY_END for stream 11629. Everything after that is the exit flushing unwanted cells at the client.)