I recently had the opportunity to travel with
Harjit to Portland Maine.
We took two different routes, one route was 5 miles longer than the other, but faster. In the image below, we took US93 North to Route 4 east over to Portsmouth NH. It's a secondary road with a bunch of stop lights and little towns. On the return trip we used 101 West (the lower track), it's longer but faster because it's all highway.
Going south to Portland:
BTV
US89 South
US93 North
NH 4 East
US95 North
250 miles: 65.1 avg m/hr
Going north to Burlington:
Portland
US95 South
US101 West
US93 North
US89 North
255 miles: 71.3 avg m/hr
We went over a couple hills too....