Set to Performance - Lower Graphical Fidelity . This can double your FPS by aggressively reducing visual load.
Set Shadows, Global Illumination, and Reflections to Off . Keep Effects and Post Processing on Low . Essential Windows & Driver Tweaks Fix FPS Drops and Boost FPS in Fortnite Chapter...
Use Fullscreen (not Windowed Fullscreen) to reduce input lag and prevent background tasks from interfering. Set to Performance - Lower Graphical Fidelity