Video game only runs well when not focused window/application

Nov 14, 2018
Intel i5 4690
Geforce 1060 6Gb
8GB DDR3 ram (unknown clock)
Windows 7 Home Premium SP1

This is a problem only with fallout 76, other games and applications have been tested and work normally, as expected.

The game started up originally running at 60fps @ 1080p. Ran perfectly fine for multiple hours. After the game was closed the first time, any new attempts to start the game now struggle around 15-20FPS when the game is the window/application in focus with very high CPU usage (98-100%), and only 20% GPU usage. No updates to the game, or any drivers in between these two events. Only playing once, shutting the game down, and restarting it.

HOWEVER now when the game is alt-tabbed or otherwise taken out of focus, the CPU usage drops significantly and GPU usage goes up to 60-70%. This is regardless of Fullscreen, Windowed, or Borderless-Windowed mode. If put in windowed/borderless-windowed mode the game visibly runs (only when not the window in focus) at 60fps again. If the game is selected as the focused window, the high fps will continue for roughly 1-2 seconds before the CPU will skyrocket and GPU usage will fall, causing abysmal framerates, as well as the mouse constantly becoming unconstrained (even in full screen exclusive).

Subsequent restarts of the game and the computer have not fixed this problem. The computer does not have a g-sync capable monitor, and g-sync has been turned off. It has, for extended periods of time run the game at 60fps before. It has a stable CPU and GPU temperature sub 70 degrees each. Antivirus has been turned off. Drivers have been uninstalled, wiped, and reinstalled. A second GPU has been tried on the computer, with the same problem.