Overview
If you’re experiencing poor FPS on Doom Eternal, try disabling the Steam Overlay (open your Steam Library, right click Doom Eternal, Properties, then disable Steam Overlay)
FPS Fix, Disable Steam Overlay
If you’re experiencing poor FPS on Doom Eternal:
1) Try disabling the Steam Overlay
(open your Steam Library, right click Doom Eternal, Properties, then disable Steam Overlay).
MSI Afterburner, Xbox DVR and Discord overlay can cause issues, too.
EDIT: It seems the Steam FPS counter specifically is causing the FPS issue. The issue has to do with the Vulkan API not handling overlays well. Doom 2016 with Vulkan had the same issue.
2) Run the game in “Fullscreen” mode.
Borderless or windowed mode can cause input lag and fps dips