Alexey Kuznetsov wrote:

If receiver sent an ACK it still does not mean that sender used it
to increase its cwnd. Particularly, small packet exchange definitely
does not inflate cwnd.

Simplest way to go about this is simply compare it to the
trace of the "good/fast" connection - Hubert, could you
provide the "good" trace as well? That would show where
the differences in time are taken up..

thanks,
Nivedita