It might be a stupid question, but as far as I understood the CNWD dictates the rate of a TCP flow.
I created a "load-balancer" that split single packets on two paths of 10Mb/s. This introduces some reordering which prevents the growth of the congestion window. When I measure the CWND for a single path (through captcp) it is around 600KB and the final goodput (with iperf3) is ~9Mb/s, if I do it with the combined paths the CNWD is around 200KB, but the final goodput is ~17Mb/s!
So how comes that the goodput is higher even if the cwnd is limiting only 200kb outstanding in the network?