Hello there!
I thought i share my experience with the game in hopes that Bethesda can take care of the Problem.
The issue is the following, i get slowdows to the mid 30s at almost any given time. Those happen everywhere, but in weird ways. I explore the wasteland and look behind me and everything is fine! Then i walk another 10 steps forward and look behind me again and im literally dropping from 60 to 30.. Its worse when i overlook a village and it doesnt matter what Settings i play the game on.. Im in and around the diamond city area and its absolutely horrendous for me sadly. Sometimes i can just look at a small lake with a small house and i drop,sometimes i just look in a random direction where there is nothing but a few Trees, and i drop. Or i look at a certain spot, slow down to 30, look 2cm to the right and bump up to 60 again.
I already tried lowering the draw distance, fpsclamp=60 and disabling vsync, nothing helped.
This is actually the exact same thing that is happening to me in Fallout 3, like, completely the same thing..
My rig is not the absolute greatest, but i think it could handle it at medium to high,
AMD Phenom III X6 1055t @ 3.81GHZ
Sapphire HD 7970 DUAL-X OC @ 1075/1550
8 GB RAM DDR3 1600
Asrock 990FX Extreme3
And a seagate barracuda
Thanks, and i hope that you devs can look into this and/or optimize this issue.