There are now in Fortnite the DirectX12 function, so it should run smoother and more consistent. However, if I turn on the feature and restart the game, the game is very strong. I have the GTX 950 graphics card from Nvidia, which should actually support DirectX12.
Does anyone have any idea of what it could be?
I would say that's because your graphics card does not support Directx 12.
Directx 12 is only supported from the rtx series.