Greetings!
I wanted to see if someone else could test my findings. It works on my setup, but I'm not certain it will fix (or alleviate) the problem with longer loading times since patch 1.3 for other people.
First: my loading times are usually fine (5-20 secs), even since 1.3. But there are some areas where I was getting up to a minute, especially downtown in the vicinity of Goodneighbor.
After deleting the INI's and playing around with lots of different settings, I narrowed it down to the GamePad setting.
With previous Bethesda titles the common wisdom for mouse/keyboard users was always to disable the gamepad in the INI's.
My results:
===> Fallout4Prefs.ini
Under [General]
bGamepadEnable=1
::Loading time just outside Goodneighbor: 25-30 seconds
bGamepadEnable=0
::Loading time just outside Goodneighbor (same save as above): 60+ seconds
Just in case: My Steam installation is in a separate Samsung 850 EVO. My OS is in a Samsung 850 Pro. Both trimmed and optimized.
Again, this worked for me, but perhaps it's something unique to my setup and my saves. It'll be nice if other people can test it and report back.