[Chrysalis]

if you need to have multiple connections to hit max speed then it means one of 3 things.

1 - tcp is tuned unoptimal, especially may be the case if an old OS like windows XP, auto tuning on windows seven should be capable tho.
2 - router is interfering with a bad mtu setting, eg. if pc is set to 1500mtu but router is 1478 then that will cause issues.
3 - congestion, can cause individual threads to slow down, but then if use multiple can get higher speeds.

in my view the vmng300 has a smaller queue depth for packets, which is why it has better latency when the ubr is congested, this possibly can have an affect on speeds as well.