Even if they could run from Springfield straight to Boston they would still have the ridiculously slow zones, like Framingham center, where the speed limit is a major factor in route time. It will never be as efficient as true high speed rail, which is unlikely to ever happen given that the existing rail can’t be moved away from those high density zones. At a minimum they would need to implement solutions like they did with the Acela grade level crossings and install more fencing along many miles of track.