I’ve followed every guide I can find, but even at 1280×1024 I get constant stuttering in-game. I’m using a GTX 1070, and I’ve watched people on YT play it just fine with less.
Check your frame rate (ALT+F). You need constant 45fps for smooth gameplay. Reduce the graphics detail (Fallout 4 launcher) or/and use the Z3D mode in vorpX if your framerate falls below 45fps. For a 1070 the “Medium” graphics preset is usually a good choice.
Try to enable FluidSync on the display page of the vorpX ingame menu. Among other things that will cap both fps values to 45fps which often can appear smoother than a fluctuating frame rate above 45fps.