Super quick and dirty modification of Uberhalit's Elden Ring FPS Unlocker. Intended to be used with Yui's Nightreign Seamless Coop OR a copy of Nightreign running with EAC OFF. This will not work without the EAC disabled!
Start Nightreign with EAC disabled (via Yui's Nightreign Seamless Coop or any other method). Launch the NightreignFPSUnlock.exe executable you downloaded from this here. Check the Frame rate lock and set it to your desired maximum FPS value. Click start game without EAC. Browse to your nightreign.exe. The executable will say "Reading game". After 5 seconds, the FPS will unlock to your value and the executable will close.
This is a quick and dirty hack of Uberhalit's elden ring FPS unlocker: https://github.com/uberhalit/EldenRingFpsUnlockAndMore
I am not going to provide any support, someone other than me is going to make a better FPS unlocker. Enjoy.