This is what I did, but depending on your tastes you can go for a higher distance:
I have been disabling vertical sync since like half life 2 came out, if not before. Usually it provides an improvement and I don't notice any of the bad things that are supposed to happen to those of us that choose to disable it. It used to help smooth tearing on CRT refresh rate problems, but it never once occured to be to enable it on an LCD screen since it was a CRT problem... maybe it was just described as a CRT issue at the time and really is a more widespread issue.
Anyway, is this still not mentioned in any tweaking guides? I am sort of surprised this wasn't one of the first things tried, to disable vsync...
vsync is such a performance problem that nvidia came up w ith their own gsync and now amd has whateversync based on some display port standard. just snake oil to me, but what do I know.
Change "iDirShadowSplits" to 2 (medium=2; high=3; ultra=3)
You can keep "Shadow Quality", "Lighting Quality" and "Decal Quality" at Ultra for almost no FPS loss.
Set "Godrays" to low or off (or bNvGodraysEnable=0 in Fallout4.ini) and for AMD users: Change the level of tesselation in your catalyst to 8x or max 16x. There might be comparable things Nvidia users can do to improve performance.
Additionally you could turn off (=0) "bVolumetricLightingEnable" in the FalloutPrefs.ini
You don't need to try all of those things mentioned above you could try one thing after the other and see how much fps you get in each case. Use Steam Overlay to measure your FPS.
Be sure to set the .ini files to "read-only" after editing them. Otherwise changing anything in Fallout's options could overwrite your manual .ini settings.
I'm running butter smooth at near Ultra settings (1080p) on a stock 760 gtx with a stock fx6300, and 16gb ram clocked at 1600mhz. It took a lot of tweaking and testing, but I finally isolated the performance culprit down to fullscreen vsync. For some reason vsync in directx 11 games is horribly broken and neither Microsoft or Nvidia seems to want to acknowledge the problem. Microsoft would rather ignore it, and Nvidia would rather sell you an overpriced gsync monitor. But anyways... here's how I managed to fix it:
Step 1.) Go download nvidia Inspector if you don't already have it. Just google it. Everyone with an nvidia card should be using this app, seriously.
Step 2.) Run nvidia Inspector and click the icon that looks like a pair of crossed tools. On the driver settings window that pops up, click on the search box in the upper left hand corner, it's labeled "Profiles" type in "fallout" and you should see "Fallout 4" in the list, click it. Under "Sync and Refresh" there is an option called "Frame Limiter" most people should be fine setting it to "60 fps" *. For the "Vertical Sync" option set that to "Force off" (this is very important). Make sure you click on the "Apply changes" button in the upper right hand corner when you are done. Close nvidia Inspector (it does not need to be running while you play the game to work since it only changes registry settings for your video drivers).
Step 3.) If you messed with anything in your Ini file for Fallout 4 I suggest you delete the file and let the game build a new one fresh. Launch Fallout 4 and set your options to "High" or lower (you can tweak up from there later once you know the game is running smoothly for you) and then set the game to run in WINDOWED BORDERLESS MODE. This is super important. If you run the game in fullscreen mode with vsync forced off in the driver settings you will get really bad screen tearing, it pretty much makes the game unplayable. But borderless window mode fixes this. Launch the game. (If you are using Steam overlay, I suggest you turn on the FPS display in the settings to help you diagnose your performance and see what framerate the game is actually rendering at rather than just "eyeballing" it)
Now, if you followed the instructions correctly, the game should be running super smooth with no stuttering and frame hitching. Why does this work? I'm not a programmer or computer engineer, but my best guess is that the vsync being used by default in fullscreen mode just plain sucks, something is faulty with it and noone wants to acknowledge the problem and take the blame to fix it. When you run the game in Windowed Borderless Mode, Windows will use it's own vsync mode that it normally uses for your desktop and windowed applications (so long as vsync was forced off for the application in the video drivers previously). Seeing as the Windows vsync works better, and the Nvidia fullscreen vsync is a broken performance hog, I'm leaning towards blaming Nvidia for this one. It probably has something to do with bad frame buffering or something technical. /shrug
* a note about locking the FPS to 60: Most of us should know by now what happens to a gamebryo engine game when you uncap the FPS beyond 60 (it pretty much breaks the engine) which is why we are capping the game to 60 fps with the utility. For those people attempting to run the game on lower hardware specs, you can follow the above instructions but cap your FPS to 30 or 45. Just trust me and try for yourselves. Even though the game runs near 60 FPS for me in most of the wasteland, it dips below that during high load and heavy city rendering. So I've got mine capped at 45 FPS and I seriously can't tell the difference between that and 60 FPS. The game runs super smooth and my video card even runs cooler during long play sessions.
Give it a try and reply back if it works out for you.
Additional Note - the settings I'm currently using are:
Resolution: 1920x1080 (Windowed Mode, Borderless)
Antialiasing: FXAA (TAA looks terrible IMO, it blurs textures when you move and pan)
Anisotropic Filtering: 16 Samples
Texture Detail: Ultra
Shadow Quality: High
Shadow Distance High
Decal Quantity: High
Lighting Quality: Ultra
Godrays Quality: Low (I think this is an important one to set as low even on high end rigs, godrays needs future optimization)
Depth of Field: Standard (I don't care for Bokeh)
Ambient Occlusion: SSAO
Everything else is ticked on, and all view distances are set around 80% and Distant Object Detail and Object Detail Fade are set to High (Ultra works for me too, but my video card runs cooler on High; I've been playing long sessions and don't want to overheat anything!)
Again, that's all on a 760 gtx, fx6300 (both on stock speeds), and the game plays amazingly smooth now. Since I've discovered this trick, I tested it out with all the other Directx 11 games that I've been having vsync stuttering with (GTA5, Shadow of Mordor, etc) and found that it fixes the issue for those games as well and they actually run smoother as if there is no more additional strain on the rendering. Hope this helps someone to enjoy Fallout 4 and maybe other games better.