after spending time confirming my pc:cable:router:modem were all running at 1gig
and my lan port drivers were up to date, it occurred to me to tweek win7/64 a bit;
https://www.speedguide.net/downloads.php
i ran this utility, set it to Optimal settings, it changed two dozen registry entries.
after a reboot i was testing within 5% of my 100/10 last mile speed.
since a lot of people are getting >50m free speed upgrades at comcast and twc,
hopefully others will find this thread and see the value of registry optimization.
it's a shame that tool developer didn't keep updating it for win8 and beyond.