Navigate to your Fallout 4 INI's Folder Usually in C:\Users\(Your name)\Documents\My Games\Fallout4
And tweak the following:
In you're Fallout4.ini
Find the following lines:
For you all these should narmally be set to 1. Change them all to 0.
Then, copy those lines.
Find your Fallout4Custom.ini and open it.
(If you do not have these lines, you've failed to follow NMM's guide to start modding)
Now, make a new header called [Display]. Copy and paste the lines you saved earlier. Now it should look a little something like this:
Finally, add a new [General] header, still in FalloutCustom.ini. And copy these lines and paste them under it:
uInterior Cell Buffer=12
uExterior Cell Buffer=144
Where the "xx" is, is where you put how many threads your CPU has. It should also slightly improve the framerate. A guide on how to find that can be found here.