It doesn't change on my desktop Sandybridge.
$ cat 4.7.0-rc6-01199-g116558d316e8/0/netperf.json
Where commit 116558d316e8 is based on top of the last test commit
98dd2532b14e with the sent_count removed.
I guess it may be because of your system memory limitation
sctp_chunk size is bigger than before, netpref produced a lot
of sctp_chunk in send queue.
can you check the memory of your systems when the test is
running, to see if memory is the bottle neck of this test ?